Image sensor and electronic camera

ABSTRACT

An image sensor includes: a plurality of filter units, transmission wavelengths of which can be adjusted; a plurality of photoelectric conversion units that receive light transmitted through the filter unit; and a control unit that alters a size of a first region containing a first filter unit, among the plurality of filter units, through which light at a first wavelength is transmitted before entering a photoelectric conversion unit.

TECHNICAL FIELD

The present invention relates to an image sensor and an electroniccamera.

There is an image sensor known in the related art that includes pixelseach having a variable filter the transmission wavelength of which canbe adjusted (PTL 1). There is an issue yet to be addressed in the imagesensor in the related art in that the resolution cannot be altered.

CITATION LIST Patent Literature

PTL 1: Japanese Laid Open Patent Publication No. 2013-85028

SUMMARY OF INVENTION

According to the 1st aspect of the present invention, an image sensorcomprises: a plurality of filter units, transmission wavelengths ofwhich can be adjusted; a plurality of photoelectric conversion unitsthat receive light transmitted through the filter unit; and a controlunit that alters a size of a first region containing a first filterunit, among the plurality of filter units, through which light at afirst wavelength is transmitted before entering a photoelectricconversion unit.

According to the 2nd aspect of the present invention, an electroniccamera comprises: the image sensor according to the 1st aspect; and animage generation unit that generates image data based upon a signalprovided by the image sensor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A block diagram showing the structure of the image capturingdevice in a first embodiment

FIG. 2 A block diagram showing the structure adopted in the image sensorin the first embodiment in an abridged presentation

FIG. 3 Diagrams illustrating the structure of the image sensor in thefirst embodiment in a sectional view

FIG. 4 A diagram showing how transmission wavelengths may be selected atthe filter units in the first embodiment

FIG. 5 Diagrams illustrating how the transmission wavelengths may beadjusted at the filter units in the first embodiment

FIG. 6 Diagrams illustrating how the filter units may be controlled inthe first embodiment

FIG. 7 A circuit diagram showing the structure adopted in a pixel in thefirst embodiment

FIG. 8 A circuit diagram showing the structure adopted in part of theimage sensor in the first embodiment

FIG. 9 Diagrams in reference to which an example of an operation thatmay be executed in the image sensor in the first embodiment will beexplained

FIG. 10 Diagrams in reference to which another example of an operationthat may be executed in the image sensor in the first embodiment will beexplained

FIG. 11 Diagrams in reference to which yet another example of anoperation that may be executed in the image sensor in the firstembodiment will be explained

FIG. 12 Diagrams in reference to which an electronic zoom function ofthe image capturing device in a second embodiment will be explained

FIG. 13 A circuit diagram showing the structure adopted in part of theimage sensor in the variation 1

FIG. 14 Diagrams in reference to which an example of an operation thatmay be executed in the image sensor in variation 1 will be explained

FIG. 15 Diagrams in reference to which another example of an operationthat may be executed in the image sensor in variation 1 will beexplained

FIG. 16 Diagrams in reference to which yet another example of anoperation that may be executed in the image sensor in variation 1 willbe explained

FIG. 17 A circuit diagram showing the structure adopted in part of theimage sensor in the variation 2

FIG. 18 Diagrams in reference to which an example of an operation thatmay be executed in the image sensor in variation 2 will be explained

FIG. 19 Diagrams in reference to which another example of an operationthat may be executed in the image sensor in variation 2 will beexplained

FIG. 20 Diagrams in reference to which yet another example of anoperation that may be executed in the image sensor in variation 2 willbe explained

FIG. 21 A circuit diagram showing the structure adopted in part of theimage sensor in variation 3

FIRST EMBODIMENT

FIG. 1 is a block diagram showing the structure of the image capturingdevice in the first embodiment. The image-capturing device in the firstembodiment may be an electronic camera 1 adopting a structure such asthat shown in FIG. 1. The electronic camera 1 comprises a photographicoptical system 2, an image sensor 3 and a control unit 4. Thephotographic optical system 2 forms a subject image at the image sensor3. The image sensor 3 generates pixel signals by capturing the subjectimage formed by the photographic optical system 2. The image sensor 3may be, for instance, a CMOS image sensor. The control unit 4 outputscontrol signals to the image sensor 3 so as to control operations of theimage sensor 3. In addition, the control unit 4 functions as an imagegeneration unit that generates image data by executing various types ofimage processing on the pixel signals output from the image sensor 3. Itis to be noted that the photographic optical system 2 may be aninterchangeable system that can be mounted at and dismounted from theelectronic camera 1.

In reference to FIG. 2 and FIG. 3, the structure of the image sensor 3in the first embodiment will be explained. FIG. 2 is a block diagramshowing the structure of part of the image sensor 3 in the firstembodiment in an abridged presentation. FIG. 3 presents diagramsillustrating the image sensor 3 in the first embodiment. FIG. 3(a)presents an example of a structure that may be adopted in the imagesensor 3 in a sectional view, whereas FIG. 3(b) illustrates howtransparent electrodes may be laid out in the filter units at the imagesensor 3 in a plan view. As shown in FIG. 2, the image sensor 3 includesa plurality of pixels 10, a filter vertical drive unit 40, a filterhorizontal drive unit 50, a filter control unit 60, a pixel verticaldrive unit 70, a column circuit unit 80, a horizontal scanning unit 90,an output unit 100 and a system control unit 110. At the image sensor 3,the pixels 10 are disposed in a two-dimensional pattern (e.g., along arow direction, i.e., along a first direction, and a column direction,i.e., a second direction intersecting the first direction). While only16 pixels (across)×12 pixels (down) are shown as the pixels 10 so as tosimplify the illustration in the example presented in FIG. 2, the imagesensor 3 actually includes, for instance, several million to severalhundred million pixels, or an even greater number of pixels.

The image sensor 3 may be, for instance, a back-illuminated imagesensor. As shown in FIG. 3(a), the image sensor 3 includes asemiconductor substrate 220, a wiring layer 210 laminated on thesemiconductor substrate 220, a support substrate 200, microlenses 31 andfilter units 5. The semiconductor substrate 220 is constituted with, forinstance, a silicon semiconductor substrate, whereas the supportsubstrate 200 is constituted with a semiconductor substrate, a glasssubstrate or the like. The semiconductor substrate 220 is laminated onthe support substrate 200 via the wiring layer 210. In the wiring layer210, which includes a conductor film (metal film) and an insulatingfilm, a plurality of wirings, vias and the like are disposed. Theconductor film may be constituted of, for instance, copper or aluminum.The insulating film may be an oxide film, a nitride film or the like. Asshown in FIG. 3(a), incident light enters the image sensor primarilytoward the + side of a Z axis. As the coordinate axes in the figureindicate, the direction running rightward on the drawing sheetperpendicular to the Z axis is designated as an X axis + direction andthe direction running away from the viewer of the drawing, perpendicularto the Z axis and the X axis, is designated as a Y axis + direction.

The semiconductor substrate 220 has a first surface 201 a used as anentry surface at which light enters and a second surface 201 b differentfrom the first surface 201 a. The second surface 201 b is located on theside opposite from the first surface 201 a. The wiring layer 210 islaminated on the side at which the second surface 201 b of thesemiconductor substrate 220 is located. Since light is radiated from theside opposite the wiring layer 210, i.e., the side on which the firstsurface 201 a is located, the image sensor 3 functions as aback-illuminated image sensor. The semiconductor substrate 220 includesphotoelectric conversion units 34 disposed in the area between the firstsurface 201 a and the second surface 201 b. At a photoelectricconversion unit 34, which may be constituted with, for instance, aphotodiode (PD), light having entered therein is converted to anelectric charge. A signal generated based upon the electric chargeresulting from the photoelectric conversion at the photoelectricconversion unit 34 is output to the wiring layer 210. A plurality ofpixels 10, each having a photoelectric conversion unit 34, are disposedalong the X axis and along the Y axis. On the side where the firstsurface 201 a of the semiconductor substrate 220 is located, a filterunit 5 and a microlens 31 are disposed in correspondence to each pixel10.

A pixel 10 is structured so as to include a microlens 31, a filter unit5, light shielding films 32 and a photoelectric conversion unit 34. Themicrolens 31 condenses light having entered therein onto thephotoelectric conversion unit 34. The light shielding films 32, eachdisposed at a boundary between pixels 10 disposed adjacent to eachother, minimize light leakage from one pixel to another.

The filter unit 5 includes electro-chromic (hereafter will be referredto as EC) layers 21, 22 and 23 and transparent electrodes 11, 12, 13 and14, laminated in sequence, starting on the side where the microlens 31is present, toward the semiconductor substrate 220. The EC layers 21through 23 are formed by using an electro-chromic material such as ametal oxide. The transparent electrodes 11 through 14 may be constitutedof, for instance, ITO (indium tin oxide). An insulating film 33 isdisposed in the areas between the EC layer 21 and the transparentelectrode 12, between the EC layer 22 and the transparent electrode 13,and between the EC layer 23 and the transparent electrode 14. Inaddition, an electrolytic layer (electrolytic film) (not shown) isdisposed in the filter unit 5.

Transparent electrodes 11 are disposed, each in correspondence to aplurality of EC layers 21 that are disposed one after another along theX direction, i.e., the row direction, so as to cover one side of thesurfaces of the plurality of EC layers 21, as is clearly shown in FIG.3(b). In the example presented in FIG. 2, the pixels 10 are arrayed overtwelve rows and thus, twelve transparent electrodes 11 are disposedparallel to one another. Transparent electrodes 12 and transparentelectrodes 13 are also disposed in much the same way as the transparentelectrodes 11, so as to cover one side of the surfaces of the pluralityof EC layers 22, disposed one after another along the X direction, orone side of the surfaces of the plurality of EC layers 23 disposed oneafter another along the X direction.

A transparent electrode 14, which is a common electrode used inconjunction with three EC layers 21, 22 and 23, is disposed on the sidewhere the other surface of the EC layer 23 is located. Commontransparent electrodes 14 are disposed, each in correspondence to theplurality of EC layers 23 that are disposed one after another along theY direction, i.e., the column direction, along the plurality of EClayers 23 disposed one after another along the column direction, as isclearly shown in FIG. 3(b). In the example presented in FIG. 2, thepixels 10 are arrayed over 16 columns, and thus, 16 common transparentelectrodes 14 are disposed parallel to one another.

The transparent electrodes 11 through 13 and the common transparentelectrodes 14 are electrodes disposed in a matrix pattern (mesh pattern)in relation to the EC layers 21, 22 and 23. The transparent electrodes11 through 13 are connected to the filter vertical drive unit 40,whereas the common transparent electrodes 14 are connected to the filterhorizontal drive unit 50. Thus, active matrix drive that enables drivecontrol for the EC layers 21, 22 and 23 can be executed by using theelectrodes disposed in the matrix pattern in the embodiment.

An EC layer 21 produces Mg (magenta) color through anoxidation-reduction reaction induced as a drive signal is provided viathe corresponding transparent electrode 11 and common transparentelectrode 14. This means that light in a wavelength range correspondingto Mg (magenta) in the incident light is transmitted through the EClayer 21 as a drive signal is provided thereto. An EC layer 22 producesYe (yellow) color through an oxidation-reduction reaction induced as adrive signal is provided via the corresponding transparent electrode 12and common transparent electrode 14. This means that light in awavelength range corresponding to Ye (yellow) in the incident light istransmitted through the EC layer 22 as a drive signal is providedthereto. An EC layer 23 produces Cy (cyan) color through anoxidation-reduction reaction induced as a drive signal is provided viathe corresponding transparent electrode 13 and common transparentelectrode 14. This means that light in a wavelength range correspondingto Cy (cyan) in the incident light is transmitted through the EC layer23 as a drive signal is provided thereto. At each EC layer among the EClayers 21, 22 and 23, the color produced as described above is sustainedover a predetermined length of time even when the drive signal is nolonger provided thereto, whereas the EC layers achieve a transparent(achromatic) state, in which light in the entire wavelength range in thelight having entered the filter unit 5 is transmitted through them whena reset signal is provided thereto.

As described above, the plurality of filter units 5 are each configuredwith three filters, i.e., an EC layer 21 that produces Mg (magenta)color, an EC layer 22 that produces Ye (yellow) color and an EC layer 23that produces Cy (cyan) color. This means that light primarily in aspecific wavelength range among the wavelength ranges corresponding toMg, Ye, Cy, W (white), BK (black), R (red), G (green) and B (blue) canbe allowed to be transmitted through a filter unit 5 by selecting aspecific combination of transmission wavelengths for the EC layers 21through 23.

The filter control unit 60 in FIG. 2 sets (adjusts) the transmissionwavelength for each filter unit 5 by controlling signals input to thefilter unit 5 from the filter vertical drive unit 40 and the filterhorizontal drive unit 50. The filter vertical drive unit 40 selects aspecific row among a plurality of rows over which filter units 5 aredisposed one after another i.e., it selects a specific transparentelectrode among the plurality of transparent electrodes 11 through 13,and provides a drive signal to the selected transparent electrode. Thefilter horizontal drive unit 50 selects a specific column among aplurality of columns in which filter units 5 are disposed side by side,i.e., it selects a specific common transparent electrode among theplurality of common transparent electrodes 14, and provides a drivesignal to the selected common transparent electrode. As a result, an EClayer corresponding to both the transparent electrode among thetransparent electrodes 11 through 13 selected by the filter verticaldrive unit 40 and the common transparent electrode 14 selected by thefilter horizontal drive unit 50 produces a color.

For instance, the filter horizontal drive unit 50 may select the commontransparent electrode 14 located at the right end, among the threecommon transparent electrodes 14 in FIG. 3(b), and provide a drivesignal to the selected common transparent electrode 14, and the filtervertical drive unit 40 may select the transparent electrode 11 locatedat the upper end among the nine transparent electrodes 11 through 13 andprovide a drive signal thereto. In such a case, the EC layer 21 locatedat the upper right end position will produce a color. In addition, ifthe filter horizontal drive unit 50 selects the same common transparentelectrode 14 and provides a drive signal thereto and the filter verticaldrive unit 40 selects the transparent electrode 12 located at the upperend and provides a drive signal thereto, the EC layer 22 at the upperright end will produce a color. If the filter horizontal drive unit 50selects the same common transparent electrode 14 and provides a drivesignal thereto and the filter vertical drive unit 40 selects thetransparent electrode 13 located at the upper end and provides a drivesignal thereto, the EC layer 23 at the upper right end will produce acolor.

The pixel vertical drive unit 70 provides control signals such as asignal TX, a signal RST and a signal SEL which will be described indetail later, to the various pixels 10, so as to control operations ofthe individual pixels 10. The system control unit 110 controls thefilter control unit 60, the pixel vertical drive unit 70, the columncircuit unit 80, the horizontal scanning unit 90 and the output unit 100based upon control signals used to control operations of the imagesensor 3, which are output from the control unit 4 in the electroniccamera 1. The system control unit 110, which includes, for instance, apulse generation circuit and the like, controls the components listedabove by outputting pulse signals and the like, generated based upon thecontrol signals provided by the control unit 4, to the filter controlunit 60 and the like.

The column circuit unit 80, configured so as to include a plurality ofanalog/digital conversion units (A/D conversion units), convertssignals, which are output from the individual pixels 10, to digitalsignals and outputs the digital signals resulting from the conversion tothe horizontal scanning unit 90. The horizontal scanning unit 90sequentially outputs the signals, having been output from the columncircuit unit 80, to the output unit 100 based upon pulse signals or thelike output from the system control unit 110. The output unit 100, whichincludes a signal processing unit (not shown), executes signalprocessing such as correlated double sampling and signal levelcorrection processing and outputs the signals having undergone thesignal processing to the control unit 4 in the electronic camera 1. Theoutput unit 100, having an input/output circuit and the like supportinga high-speed interface such as LVDS and SLVS, is able to transmit thesignals to the control unit 4 at high speed.

FIG. 4 shows how transmission wavelengths may be selected at the filterunits in the first embodiment. In the example presented in FIG. 4, thefilter unit 5 is set in a state in which light in a wavelength range forW (white), BK (black), Mg (magenta), Ye (yellow), Cy (cyan), R (red), G(green) or B (blue) is primarily transmitted by selecting a specificcombination of transmission wavelengths for the EC layers 21 through 23.

In FIG. 4, Mg inside a dash-line frame indicates a state in which lightin the Mg wavelength range is transmitted through the EC layer 21. Yeinside a dash-line frame indicates a state in which light in the Yewavelength range is transmitted through the EC layer 22. Cy inside adash-line frame indicates a state in which light in the Cy wavelengthrange is transmitted through the EC layer 23. In addition, a dotted-lineframe indicates that the corresponding EC layer is in a transparent(achromatic) state in which light in the entire wavelength range istransmitted through the EC layer. W, BK, Mg, Ye, Cy, R, G or B inside asolid-line frame indicates the wavelength range of light transmittedthrough the three EC layers 21, 22 and 23 (three-layer EC transmissionwavelength range).

When a drive signal is provided to an EC layer 21, the EC layer 21enters a state in which it absorbs light in the G wavelength range andallows light in the R wavelength range and light in the B wavelengthrange to be transmitted, i.e., a state in which light in the Mgwavelength range is transmitted. In addition, when a drive signal isprovided to an EC layer 22, the EC layer 22 enters a state in which itabsorbs light in the B wavelength range and allows light in the Rwavelength range and light in the G wavelength range to be transmitted,i.e., a state in which light in the Ye wavelength range is transmitted.Moreover, when a drive signal is provided to an EC layer 23, the EClayer 23 enters a state in which it absorbs light in the R wavelengthrange and allows light in the G wavelength range and light in the Bwavelength range to be transmitted, i.e., a state in which light in theCy wavelength range is transmitted.

When a drive signal is provided to the EC layer 21 alone, the EC layer22 alone or the EC layer 23 alone among the three EC layers 21, 22 and23, the three-layer EC transmission wavelength range for Mg (magenta),Ye (yellow) or Cy (cyan) is set. In addition, when drive signals areprovided to both the EC layer 21 and the EC layer 22, the three-layer ECtransmission wavelength range for R (red) is set, when drive signals areprovided to both the EC layer 22 and the EC layer 23, the three-layer ECtransmission wavelength range for G (green) is set, and when drivesignals are provided to both the EC layer 21 and the EC layer 23, thethree-layer EC transmission wavelength range for B (blue) is set. Whenno drive signal is provided to any of the EC layers 21, 22 and 23, lightin the full wavelength range is transmitted through all the EC layers 21through 23 and thus, the three-layer EC transmission wavelength rangefor W (white) is set. When drive signals are provided to all three EClayers 21, 22 and 23, light in the G wavelength range is absorbed in theEC layer 21, light in the B wavelength range is absorbed in the EC layer22 and light in the R wavelength range is absorbed in the EC layer 23,thereby setting the three-layer EC transmission wavelength range for BK(black).

FIG. 5 illustrates how the transmission wavelengths may be altered atthe filter units 5 in the first embodiment. It is to be noted that forpurposes of simplification, filter units 5 in only four pixels(across)×four pixels (down) taking positions at a coordinate point (1,1) through a coordinate point (4, 4) are shown in FIG. 5. FIGS. 5(a)through 5(g) illustrate in time sequence how the four×four pixels,initially all set in a W (white) state, shift into a state in which theyform an RGB Bayer array pattern, as a voltage is sequentially applied tospecific transparent electrodes among the transparent electrodes 11through 14 in the individual filter units 5.

In the initial state shown in FIG. 5(a), all the filter units 5 are in astate in which the entering light is transmitted over its fullwavelength range, i.e., all the filter units 5 function as W filterunits 5. The filter control unit 60 may supply a positive potential tothe transparent electrodes 11 through 13 in all the filter units 5 andsupply a negative potential to the common transparent electrodes 14 inall the filter units 5 so as to cause the EC layers 21 through 23 in atransparent (achromatic) state, in which light entering the filter units5 is transmitted in its full wavelength range.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(b) by applying voltages, which are the opposite ofthose applied to cause the EC layers achromatic, to the commonelectrodes 14 at the filter units 5 in the first column and the thirdcolumn and to the transparent electrodes 11 at the filter units 5 in thefirst row and the third row, i.e., it applies a positive potential tothe common transparent electrodes 14 and a negative potential to thetransparent electrodes 11. As a result, the filter units 5 at thecoordinate points (1, 1), (1, 3), (3, 1) and (3, 3) enter a state inwhich magenta color is produced at the EC layers 21 and thus, the filterunits 5 at these four coordinate point positions function as Mg filterunits 5, through which light primarily in the magenta wavelength rangeis transmitted. In addition, while the voltage application to the filterunits 5 at the coordinate points (1, 1), (1, 3), (3, 1) and (3, 3) stopsafter the voltage is applied over a predetermined length of time, thecolor will be sustained over a specific length of time due to the“memory effect” at the EC layers.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(c) by applying a positive potential to the commontransparent electrodes 14 at the filter units 5 in the second column andthe fourth column and applying a negative potential to the transparentelectrodes 11 at the filter units 5 in the second row and the fourthrow. As a result, the filter units 5 at the coordinate points (2, 2),(2, 4), (4, 2) and (4, 4) enter a state in which magenta color isproduced at the EC layers 21 and thus, the filter units 5 at thesecoordinate point positions function as Mg filter units 5.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(d) by applying a positive potential to the commontransparent electrodes 14 at the filter units 5 in the first column andthe third column and applying a negative potential to the transparentelectrodes 12 at the filter units 5 in the first row through the fourthrow. As a result, the filter units 5 at the coordinate points (2, 1),(2, 3), (4, 1) and (4, 3) enter a state in which yellow color isproduced at the EC layers 22 and thus, the filter units 5 at thesecoordinate point positions function as Ye filter units 5, through whichlight primarily in the yellow wavelength range is transmitted. Inaddition, the filter units 5 at the coordinate points (1, 1), (1, 3),(3, 1) and (3, 3), where the EC layers 21 enter a state of magenta colorproduction and the EC layers 22 enter a state of yellow colorproduction, are caused to function as R filter units 5 through whichlight primarily in the red wavelength range is transmitted.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(e) by applying a voltage to the common transparentelectrodes 14 at the filter units 5 in the second column and the fourthcolumn and applying a voltage to the transparent electrodes 12 at thefilter units 5 in the first row and the third row. As a result, thefilter units 5 at the coordinate points (1, 2), (1, 4), (3, 2) and (3,4) enter a state in which yellow color is produced at the EC layers 22and thus, the filter units 5 at these coordinate point positionsfunction as Ye filter units 5.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(f) by applying a voltage to the common transparentelectrodes 14 at the filter units 5 in the first column and the thirdcolumn and applying a voltage to the transparent electrodes 13 at thefilter units 5 in the second row and the fourth row. As a result, thefilter units 5 at the coordinate points (2, 1), (2, 3), (4, 1) and (4,3) enter a state in which yellow color is produced at the EC layers 22and cyan color is produced at the EC layers 23, thereby causing thefilter units 5 to function as G filter units 5 through which lightprimarily in the green wavelength range is transmitted.

The filter control unit 60 executes control to achieve the conditionillustrated in FIG. 5(g) by applying a voltage to the common transparentelectrodes 14 at the filter units 5 in the second column and the fourthcolumn and applying a voltage to the transparent electrodes 13 at thefilter units 5 in the first row through the fourth row. As a result, thefilter units 5 at the coordinate points (1, 2), (1, 4), (3, 2) and (3,4) enter a state in which yellow color is produced at the EC layers 23and cyan color is produced, thereby causing the filter units 5 tofunction as a G filter units 5. In addition, the filter units 5 at thecoordinate points (2, 2), (2, 4), (4, 2) and (4, 4), where the EC layers21 enter a state of magenta color production and the EC layers 23 entera state of cyan color production, are caused to function as B filterunits 5 through which light primarily in the blue wavelength range istransmitted.

The filter control unit 60 is capable of controlling the filter units 5in the pixels 10 so as to form a Bayer array pattern with R pixelshaving R filter units 5, G pixels having G filter units 5 and B pixelshaving B filter units 5 as illustrated in FIG. 5(g). As described above,the filter control unit 60 in the embodiment is able to alter thetransmission wavelength at each filter unit 5 through sequential controlof the transmission wavelength at the individual filter units 5. Inaddition, the filter control unit 60 is able to simultaneously controlthe transmission wavelengths at the plurality of filter units 5 disposedalong the row direction or the column direction by providing electricsignals via the transparent electrodes 11 through 14 disposed in amatrix pattern and then and stopping the electric signals.

The image sensor 3 in the embodiment is capable of executing processingthrough which signals are individually read out from all the pixels 10and processing through which signals, each representing the sum ofsignals generated at a plurality of pixels 10, are read out, as will beexplained in detail below. The image sensor 3 may execute the processingthrough which the signals generated at all the pixels 10 in the imagesensor 3 are individually read out when photographing a still image,whereas it may execute the processing for reading out signals eachrepresenting the sum of signals generated at a plurality of pixels 10when shooting movie. In addition, while the image sensor 3 may includean extremely large number of pixels (e.g., several hundred millionpixels), it is rare that a display device capable of displaying ahigh-resolution image expressed with the extremely large number ofpixels in the image sensor is used. Accordingly, addition processing foradding together signals generated at a plurality of pixels 10 will beexecuted so as to generate signals in a quantity corresponding to thenumber of pixels required to express an image brought up on display atthe display device in use. The “addition processing” executed under suchcircumstances includes averaging processing through which a plurality ofsignals are added together and averaged, weighted addition processingthrough which a plurality of signals are first weighted and addedtogether, and the like. It is to be noted that the method that may beadopted when generating a signal by using signals generated at aplurality of pixels is not limited to these examples.

FIG. 6 presents examples of control that may be executed on the filterunits 5 in the first embodiment. As explained earlier, the filtercontrol unit 60 is able to create R pixels having R filter units 5, Gpixels having G filter units 5 and B pixels having B filter units 5 bysetting specific transmission wavelengths for the individual filterunits 5. In the example presented in FIG. 6(a), a region 41Acorresponding to a single R pixel, a region 42A and a region 43A eachcorresponding to a single G pixel and a region 44A corresponding to asingle B pixel together constitute a Bayer array basic unit (41A, 42A,43A and 44A). At the image sensor 3, the disposition of the 2 pixels×2pixels basic unit (41A, 42A, 43A and 44A) is reiterated.

In the example presented in FIG. 6(b), a region 41B that contains 2×2=4R pixels, a region 42B and a region 43B each of which contains 2×2=4 Gpixels, and a region 44B that contains 2×2=4 B pixels are set in a Bayerarray pattern. In the example presented in FIG. 6(b), the 4×4 pixelspresent in the regions 41B through 44B form a Bayer array reiteratingbasic unit. In the example in FIG. 6(c) a region 41C that contains 3×3=9R pixels, a region 42C and a region 43C each of which contains 3×3=9 Gpixels, and a region 44C that contains 3×3=9 B pixels are set in a Bayerarray pattern. In the example in FIG. 6(c), the 6×6 pixels present inthe regions 41C through 44C together form a Bayer array reiteratingbasic unit. Namely, the filter control unit 60 in the embodiment is ableto adjust the size of the Bayer array basic unit by controlling thefilter units 5 so as to set the same transmission wavelength range forthe filter units 5 in a plurality of pixels disposed adjacent to eachother. In other words, the size of the Bayer array basic unit can beadjusted to that made up with the regions 41A through 44A, where 2×2pixels are present, to that made up with regions 41B through 44B, where4×4 pixels are present or to that made up with the regions 44C through44C where 6×6 pixels are present.

When the regions 41B, 42B, 43B and 44B constituting the basic unit areeach made up with 2×2=4 pixels, as shown in FIG. 6(b), a sum pixelsignal is generated through addition processing executed by addingtogether the pixel signals from the four pixels in each region. Morespecifically, the image sensor 3 generates sum pixel signals each byadding together the pixel signals generated at the 2×2=4 pixels in oneof the plurality of regions 41B through 44B, as will be explained later.As a result, when sum pixel signals are output by controlling thetransmission wavelength ranges at the filter units 5, as shown in FIG.6(b), the resolution is lowered to ¼ that of an image expressed withsignals individually output from the individual pixels, as shown in FIG.6(a). Likewise, when the regions 41C, 42C, 43C and 44C constituting thebasic unit are each made up with 3×3=9 pixels, as shown in FIG. 6(c), asum pixel signal is generated through addition processing executed byadding together the pixel signals from the nine pixels in each region.As a result, when sum pixel signals are output by controlling thetransmission wavelength ranges at the filter units 5, as shown in FIG.6(c), the resolution is lowered to 1/9 that of an image expressed withsignals individually output from the individual pixels, as shown in FIG.6(a).

It is to be noted that instead of adding together the pixel signalsgenerated at the four pixels in each of the regions 41B through 44B oradding together the pixel signals generated at the nine pixels in eachof the regions 41C through 44C through addition processing executedwithin the image sensor 3, as will be explained later in reference toFIG. 8, pixel signals originating from the image sensor 3 may undergoaddition processing in the control unit 4 shown in FIG. 1.

It is desirable that the electronic camera 1 capture an image at highresolution when the number of display pixels at the display device atwhich image data generated in the image sensor 3 are brought up ondisplay is substantially equal to the number of pixels at the imagesensor 3 and that it capture an image at a relatively low resolution ifthe number of display pixels is smaller than the number of pixels at theimage sensor 3. Likewise, it is desirable that the electronic camera 1capture an image at high resolution when an image expressed with theimage data is to be printed out in a large format and that it capture animage at low resolution if the image expressed with the image data is tobe printed out in a small size.

Accordingly, if the electronic camera 1 in the embodiment is set in ahigh-resolution photographing mode via, for instance, an operation unit(not shown), the filter control unit 60 controls the filter units 5 inthe individual pixels 10, as shown in FIG. 6(a). Likewise, if theelectronic camera 1 is set in a lower-resolution photographing mode via,for instance, the operation unit (not shown), the filter control unit 60controls the filter units 5 in the individual pixels 10, as shown inFIG. 6(b) or 6(c).

In addition, if the electronic camera 1 is set in a still imagephotographing mode via the operation unit (not shown), the filtercontrol unit 60 controls the filter units 5 at the individual pixels 10,as shown in FIG. 6(a) so as to obtain high-resolution image data. If, onthe other hand, the electronic camera 1 is set in a movie shooting modevia the operation unit (not shown), the filter control unit 60 controlsthe filter units 5 in the individual pixels 10, as shown in FIG. 6(b) orFIG. 6(c) so as to achieve a high frame rate.

An image sensor, having filter units with fixed transmission wavelengthsdisposed in a Bayer array, needs to add together signals generated at aplurality of same-color pixels corresponding to a given color, which aredisposed at positions set apart from one another. In this situation, thesignal generated at a pixel corresponding to a different color presentbetween the same-color pixels will not be used and thus will be wasted.Furthermore, color mixing may occur in the same-color pixel signals tobe added together, due to crosstalk from different-color pixels adjacentto the same-color pixels.

The regions 41A through 44A, the regions 41B through 44B or the regions41C through 44C, constituting the Bayer array basic unit in theembodiment, are each invariably made up with same-color pixels. Thismeans that the signals generated at the same-color pixels within eachregion 41 through 44 can be added together. Since the filter units 5 inadjacent pixels correspond to the same color, crosstalk from a pixelhaving a different-color filter unit can be limited.

In reference to FIG. 7 and FIG. 8, the circuit structure adopted in theimage sensor 3 in the first embodiment will be explained. FIG. 7 is acircuit diagram showing the structure adopted in a pixel 10 in the firstembodiment. FIG. 8 is a circuit diagram showing the structure in part ofthe image sensor 3 in the first embodiment. The pixels 10 each include aphotoelectric conversion unit 34 and a readout unit 20. Thephotoelectric conversion unit 34 has a function of converting lighthaving entered therein to an electric charge and accumulating theelectric charge resulting from the photoelectric conversion. The readoutunit 20 includes a transfer unit 25, a reset unit 26, a floatingdiffusion 27, an amplifier unit 28, a selection unit 29, a first switchunit 18 and a second switch unit 19.

The transfer unit 25 transfers the electric charge resulting from thephotoelectric conversion executed at the photoelectric conversion unit34 to the floating diffusion 27 under control executed based upon asignal TX. Namely, the transfer unit 25 forms an electric chargetransfer path between the photoelectric conversion unit 34 and thefloating diffusion 27. The electric charge is accumulated (held) in acapacitance FD at the floating diffusion 27. The amplifier unit 28amplifies a signal generated based upon the electric charge held in thecapacitance FD and outputs the amplified signal. In the examplepresented in FIG. 7, the amplifier unit 28 is configured with atransistor M3, a drain terminal, a gate terminal and a source terminalof which are respectively connected to a source VDD, the floatingdiffusion 27 and the selection unit 29. The source terminal of theamplifier unit 28 is connected to a vertical signal line 101 via theselection unit 29. The amplifier unit 28 functions as part of a sourcefollower circuit that uses a current source 81 shown in FIG. 8 as a loadcurrent source.

The reset unit 26, which is controlled based upon a signal RST, resetsthe electric charge at the capacitance FD and resets the potential atthe floating diffusion 27 to a reset potential (reference potential).The selection unit 29, which is controlled based upon a signal SEL,outputs the signal provided from the amplifier unit 28 to the verticalsignal line 101. The transfer unit 25, the reset unit 26 and theselection unit 29 may be respectively configured with, for instance, atransistor M1, a transistor M2 and a transistor M4.

Via first switch units 18, each controlled with a signal SW_X, thefloating diffusions 27 in a plurality of pixels 10 disposed side-by-sidealong the row direction (the first direction) are connected as shown inFIG. 8. Via second switch units 19, each controlled with a signal SW_Y,the floating diffusions 27 in a plurality of pixels 10 disposedside-by-side along the column direction (the second direction) areconnected as shown in FIG. 8. A first switch unit 18 and a second switchunit 19 may be constituted with, for instance, a transistor M5 and atransistor M6 respectively.

The readout unit 20 reads out a signal (pixel signal) corresponding toan electric charge transferred by the transfer unit 25 from thephotoelectric conversion unit 34 to the floating diffusion 27 and asignal (noise signal) generated when the potential at the floatingdiffusion 27 is reset to the reset potential, to the vertical signalline 101.

As shown in FIG. 8, the image sensor 3 includes a plurality of pixels 10disposed in a matrix pattern, the pixel vertical drive unit 70 and thecolumn circuit unit 80. The column circuit unit 80 includes currentsources 81 (current source 81 a through current source 81 d) and A/Dconversion units 82 (A/D conversion unit 82 a through A/D conversionunit 82 d). The current sources 81 and the A/D conversion units 82 areeach disposed in correspondence to one of the pixel columns each made upwith a plurality of pixels disposed side-by-side along the columndirection, i.e., along the longitudinal direction. In addition, verticalsignal lines 101 (vertical signal line 101 a through vertical signalline 101 d) are disposed each in correspondence to one of the columnsmade up with pixels 10. It is to be noted that only a small number ofpixels 10, i.e., four pixels (across)×four pixels (down), are shown inFIG. 8 so as to simplify the illustration. Among the plurality of pixels10 shown in FIG. 8, the pixel 10 taking the lower left position isdesignated as a first row/first column pixel 10 (1, 1), and FIG. 8 showsthe pixel 10 (1, 1) through the pixel 10 (4, 4).

The pixel vertical drive unit 70 provides a signal TX, a signal RST, asignal SEL, a signal SW_X and a signal SW_Y to each pixel 10. A currentsource 81, which is connected via the corresponding vertical signal line101 with the individual pixels 10, generates a current to be used forreading out the pixel signal and the noise signal from each pixel 10.The current source 81 supplies the electric current that it hasgenerated to the corresponding vertical signal line 101 and pixels 10.An A/D conversion unit 82 converts signals output to the correspondingvertical signal line 101 to digital signals.

In the embodiment, the pixel vertical drive unit 70, the first switchunits 18, the second switch units 19, and the capacitances FD togetherfunction as an adder unit that adds together signals provided from thephotoelectric conversion units 34. In more specific terms, the pixelvertical drive unit 70 outputs signals SW_X and signals SW_Y to theindividual pixels 10 and executes ON/OFF control for the first switchunits 18 and the second switch units 19 therein so as to executeaddition processing for adding together signals originating in theplurality of photoelectric conversion units 34.

FIG. 9 illustrates how an operation may be executed in the image sensor3 in the first embodiment. FIG. 9(a) shows a Bayer array reiteratingbasic unit made up with 2×2 pixels present in regions 41A through 44A.FIG. 9(b) is a timing chart of an operation that may be executed in theimage sensor 3 when the transmission wavelengths at the filter units 5are set as shown in FIG. 9(a). In FIG. 9(b), time points are indicatedalong the horizontal axis. In the timing chart in FIG. 9(b), atransistor to which a high-level control signal (e.g., at the sourcepotential) is input, enters an ON state and a transistor to which alow-level control signal (e.g., at the ground potential) is input,enters an OFF state.

At a time point t1, a signal RST1 shifts to high level, thereby settingthe transistors M2 constituting the reset units 26 in an ON state andsetting the potentials at the floating diffusions 27 to the resetpotential at the pixels 10 (1, 1) through 10 (1, 4) in the first row. Inaddition, at the time point t1, signals SEL1 a through SEL1 f shift tohigh level and, as a result, noise signals originating at the pixel 10(1, 1) through the pixel 10 (1, 4) are respectively output to a verticalsignal line 101 a through a vertical signal line 101 d via thetransistors M3 constituting the amplifier units 28 and the transistorsM4 constituting the selection units 29. The noise signals from thepixels 10 in the first row, individually output to the vertical signalline 101 a through the vertical signal line 101 d, are respectivelyinput to the A/D conversion unit 82 a through the A/D conversion unit 82d where they are converted to digital signals.

At a time point t2, a signal TX1 shifts to high level, thereby settingthe transistors M1 constituting the transfer units 25 in an ON state atthe pixel 10 (1, 1) through the pixel 10 (1, 4) in the first row. As aresult, electric charges resulting from photoelectric conversionexecuted in a PD11 through a PD14 are respectively transferred to acapacitance FD11 through a capacitance FD14 at the individual floatingdiffusions 27. The electric charges having been transferred areaccumulated in the capacitances FD11 through FD14 at the floatingdiffusions 27. In addition, since the signals SEL1 a through SEL1 f areat high level at the time point t2, pixel signals at the pixel 10 (1, 1)through the pixel 10 (1, 4) are respectively output to the verticalsignal line 101 a through the vertical signal line 101 d via thecorresponding amplifier units 28 and selection units 29. The pixelsignals output from the pixels 10 in the first row to the verticalsignal line 101 a through the vertical signal line 101 d arerespectively input to the A/D conversion unit 82 a through the A/Dconversion unit 82 d where they are converted to digital signals.

During a time period elapsing between a time point t3 and a time pointt5, noise signals and pixel signals originating at the pixels 10(2, 1)through 10 (2, 4) in the second row are read out in the same way as thesignals are read out over the time period elapsing between the timepoint t1 and the time point t3. Likewise, noise signals and pixelsignals originating at the pixels 10 (3, 1) through 10 (3, 4) in thethird row are read out over a time period elapsing between the timepoint t5 and a time point t7, and noise signals and pixel signalsoriginating at the pixels 10 (4, 1) through 10 (4, 4) in the fourth roware read out over a time period elapsing between the time point t7 and atime point t9. In addition, the noise signals and the pixel signals,converted to digital signals at the A/D conversion units 82, are inputto the output unit 100 via the horizontal scanning unit 90 shown in FIG.2. The output unit 100 executes differential processing with respect tothe noise signals and the pixel signals having originated in the pixels10 through correlated double sampling. Through the embodiment describedabove, pixel signals at the pixels can be individually read out when theregions 41A through 44A constituting the Bayer array basic unit are eachmade up with a single pixel.

FIG. 10 presents another example of an operation that may be executed inthe image sensor 3 in the first embodiment. FIG. 10(a) shows a Bayerarray reiterating basic unit made up with 4×4 pixels present in regions41B through 44B. FIG. 10(b) is a timing chart of an operation that maybe executed in the image sensor 3 when the transmission wavelengths atthe filter units 5 are set as shown in FIG. 10(a).

At a time point t1, a signal SW_X1 a, a signal SW_X2 a and a signalSW_Y1 shift to high level, thereby electrically connecting thecapacitances at four pixels 10, i.e., the capacitance FD11 at the pixel10 (1, 1), the capacitance FD12 at the pixel 10 (1, 2), the capacitanceFD21 at the pixel 10 (2, 1) and the capacitance FD22 at the pixel 10 (2,2), with one another. In addition, at the time point t1, a signal SW_X1c, a signal SW_X2 c and the signal SW_Y1 shift to high level, therebyelectrically connecting the capacitances at four pixels 10, i.e., thecapacitance FD13 at the pixel 10 (1, 3), the capacitance FD14 at thepixel 10 (1, 4), the capacitance FD23 at the pixel 10 (2, 3) and thecapacitance FD24 at the pixel 10 (2, 4), with one another.

Furthermore, at the time point t1, a signal RST1 and a signal RST2 shiftto high level, thereby turning on the transistors M2 constituting thereset units 26 and setting the potentials at the floating diffusions 27to the reset potential at the pixels 10 (1, 1) through 10 (1, 4) and thepixels 10 (2, 1) through 10 (2, 4). In this situation, since thecapacitances FD at the four pixels 10 are connected as explainedearlier, the potentials at the floating diffusions 27 in the pixel 10(1, 1), the pixel 10 (1, 2), the pixel 10 (2, 1) and the pixel 10 (2, 2)are averaged. In addition, the potentials at the floating diffusions 27in the pixel 10 (1, 3), the pixel 10 (1, 4), the pixel 10 (2, 3) and thepixel 10 (2, 4) are averaged.

Additionally, as a signal SEL1 a shifts to high level at the time pointt1, a noise signal generated by averaging signals at the four pixels,i.e., the pixel 10 (1, 1), the pixel 10 (1, 2), the pixel 10 (2, 1) andthe pixel 10 (2, 2), is output to the vertical signal line 101 a via theamplifier unit 28 and the selection unit 29 at the pixel 10 (1, 1). Thenoise signal output to the vertical signal line 101 a is input to theA/D conversion unit 82 a, which then converts it to a digital signal.Moreover, as a signal SEL1 c shifts to high level at the time point t1,a noise signal generated by averaging signals at the four pixels, i.e.,the pixel 10 (1, 3), the pixel 10 (1, 4), the pixel 10 (2, 3) and thepixel 10 (2, 4), is output to the vertical signal line 101 c via theamplifier unit 28 and the selection unit 29 at the pixel 10 (1, 3). Thenoise signal output to the vertical signal line 101 c is input to theA/D conversion unit 82 c, which then converts it to a digital signal.

At a time point t2, a signal TX1 and a signal TX2 shift to high levelthereby turning on the transistors M1 constituting the transfer units 25to transfer electric charges resulting from photoelectric conversionexecuted in the PDs 11 through 14 and the PDs 21 through PD24, to thecorresponding floating diffusions 27 at the pixels 10 (1, 1) through 10(1, 4) and the pixels 10 (2, 1) through 10 (2, 4). Since thecapacitances FD in the four pixels 10 are connected with one another asexplained earlier, the electric charges transferred from the fourcorresponding PDs, i.e., the PD11, the PD12, the PD21 and the PD22, aredistributed among the four capacitances FD11, FD12, FD21 and FD22. Inaddition, the electric charges transferred from the four PDs 13, 14, 23and 24 are distributed among the four capacitances FD13, FD14, FD23 andFD24.

At the time point t2, the signal SEL1 a is at high level and thus, a sumpixel signal generated by averaging signals at the four pixels, i.e.,the pixel 10 (1, 1), the pixel 10 (1, 2), the pixel 10 (2, 1) and thepixel 10 (2, 2), is output to the vertical signal line 101 a via theamplifier unit 28 and the selection unit 29 at the pixel 10 (1, 1). Thesum pixel signal output to the vertical signal line 101 a is input tothe A/D conversion unit 82 a which then converts it to a digital signal.Furthermore, at the time point t2, the signal SEL1 c is at high leveland thus, a sum pixel signal generated by averaging signals at the fourpixels, i.e., the pixel 10 (1, 3), the pixel 10 (1, 4), the pixel 10 (2,3) and the pixel 10 (2, 4), is output to the vertical signal line 101 cvia the amplifier unit 28 and the selection unit 29 at the pixel 10 (1,3). The sum pixel signal output to the vertical signal line 101 c isinput to the A/D conversion unit 82 c which then converts it to adigital signal. The noise signals and the sum pixel signals having beenconverted to digital signals at the A/D conversion units 82 are input tothe output unit 100 via the horizontal scanning unit 90 shown in FIG. 2.The output unit 100 executes differential processing to determine thedifferences between the noise signals and the sum pixel signalsoriginating at the pixels 10 through correlated double sampling.

During a time period elapsing between a time point t3 and a time pointt5, signals generated by adding together and averaging signals at thepixel 10 (3, 1), the pixel 10 (3, 2), the pixel 10 (4, 1) and the pixel10 (4, 2) and signals generated by adding together and averaging signalsgenerated at the pixel 10 (3, 3), the pixel 10 (3, 4), the pixel 10 (4,3) and the pixel 10 (4, 4) are read out in the same way as signals areread out during the time period elapsing between the time point t1 andthe time point t3. During a time period elapsing between the time pointt5 and a time point t7, signals generated by adding together andaveraging signals at the pixel 10 (5, 1), the pixel 10 (5, 2), the pixel10 (6, 1) and the pixel 10 (6, 2) and signals generated by addingtogether and averaging signals generated at the pixel 10 (5, 3), thepixel 10 (5, 4), the pixel 10 (6, 3) and the pixel 10 (6, 4) are readout in the same way as signals are read out during the time periodelapsing between the time point t1 and the time point t3. In thisembodiment, a signal can be read out by adding together the signals atthe four pixels present in each region in conjunction with a Bayer arraybasic unit constituted with the regions 41B through 44B, each made upwith 2×2=4 pixels.

In addition, a sum pixel signal obtained by adding together the signalsgenerated at the four pixels is read out to the vertical signal line 101a or the vertical signal line 101 c in the example presented in FIG. 10.Since this allows current generation at the current sources 81 b and 81d, connected to the vertical signal lines 101 b and 101 d, to which nosum pixel signals are read out, to be stopped, the level of currentconsumption in the image sensor 3 can be lowered.

FIG. 11 presents yet another example of an operation that may beexecuted in the image sensor 3 in the first embodiment. FIG. 11(a) showsa Bayer array reiterating basic unit made up with 6×6 pixels present inregions 41C through 44C. FIG. 11(b) is a timing chart of an operationthat may be executed in the image sensor 3 when the transmissionwavelengths at the filter units 5 are set as shown in FIG. 11(a).

At a time point t1, a signal SW_X1 a, a signal SW_X1 b, a signal SW_X2a, a signal SW_X2 b, a signal SW_X3 a, a signal SW_X3 b, a signal SW_Y1and a signal SW_Y2 shift to high level, thereby electrically connectingthe capacitances at nine pixels 10, i.e., the capacitance FD11 at thepixel 10 (1, 1), the capacitance FD12 at the pixel 10 (1, 2), thecapacitance FD13 at the pixel 10 (1, 3), the capacitance FD21 at thepixel 10 (2, 1), the capacitance FD22 at the pixel 10 (2, 2), thecapacitance FD23 at the pixel 10 (2, 3), the capacitance FD31 at thepixel 10 (3, 1), the capacitance FD32 at the pixel 10 (3, 2) and thecapacitance FD33 at the pixel 10 (3, 3) with one another.

In addition, at the time point t1, a signal RST1, a signal RST2 and asignal RST3 shift to high level, thereby turning on the transistors M2constituting the reset units 26 and setting the potentials at thefloating diffusions 27 to the reset potential at the pixels 10 (1, 1)through 10 (1, 3), the pixels 10 (2, 1) through 10 (2, 3) and the pixels10 (3, 1) through 10 (3, 3). In this case, the potentials at thefloating diffusions 27 are averaged in the capacitances FD at the ninepixels 10 listed above.

Furthermore, as a signal SEL2 b shifts to high level at the time pointt1, a noise signal generated by averaging signals at the nine pixels isoutput to the vertical signal line 101 b via the amplifier unit 28 andthe selection unit 29 at the pixel 10 (2, 2). The noise signal output tothe vertical signal line 101 b is input to the A/D conversion unit 82 b,which then converts it to a digital signal.

At a time point t2, a signal TX1, a signal TX2 and a signal TX3 shift tohigh level, thereby turning on the transistors M1 constituting thetransfer units 25 to transfer electric charges resulting fromphotoelectric conversion executed at the PDs 11 through 13, the PDs 21through 23 and the PDs 31 through 33 to the corresponding floatingdiffusions 27 at the pixels 10 (1, 1) through 10 (1, 3), the pixels 10(2, 1) through 10 (2, 3) and the pixels 10 (3, 1) through 10 (3, 3). Theelectric charges transferred from the nine PDs, i.e., the PD11 throughthe PD13, the PD21 through the PD23, and the PD31 through the PD33, aredistributed among the nine capacitances FD11, FD12, FD13, FD21, FD22,FD23, FD31, FD32 and FD33.

In addition, at the time point t2, the signal SEL2 b is at high leveland thus, a sum pixel signal generated by averaging signals generated atthe nine pixels is output to the vertical signal line 101 b via theamplifier unit 28 and the selection unit 29 at the pixel 10 (2, 2). Thesum pixel signal output to the vertical signal line 101 b is input tothe A/D conversion unit 82 b which then converts it to a digital signal.In this embodiment, a signal can be read out by adding together thesignals at the nine pixels present in each region in conjunction with aBayer array basic unit constituted with the regions 41C through 44C,each made up with 3×3=9 pixels.

In addition, a sum pixel signal obtained by adding together the signalsgenerated at the nine pixels is read out to the vertical signal line 101b in the example presented in FIG. 11. Since this allows currentgeneration at the current sources 81 a and 81 c, connected to thevertical signal lines 101 a and 101 c, to which no sum pixel signals areread out, to be stopped, the level of current consumption in the imagesensor 3 can be lowered.

It is to be noted that while addition processing for adding togethersignals generated at the individual pixels is executed within the pixels10 in the embodiment described above, the pixel signals generated at thepixels 10 may be individually output to the output unit 100 and additionprocessing may be executed in the output unit 100, instead.

The power consumption and the length of time required for signal readoutare bound to increase if the signals from all the pixels 10 are to beread out individually in an image sensor 3 having a very large number ofpixels, to satisfy the requirements of, for instance, surveillance orindustrial applications. In the embodiment, the size of the area thatincludes R, G and B filter units 5 is altered while sustaining the Bayerarray pattern so as to make it possible to output a signal generated byadding together the signals generated at a plurality of pixels 10adjacent to one another. Since the signals generated at adjacent pixelsare added together, the level of noise in the signal and the currentconsumption can both be lowered in comparison to signal generationexecuted by adding together signals generated at pixels at positions setapart from one another. In addition, since the signals from adjacentpixels are added together, the length of time required for the additionprocessing can be reduced over the length of time required for additionprocessing executed by adding together signals at pixels disposed atpositions set apart from one another, which makes it possible to reducethe length of time required for pixel signal readout.

The following advantages and operations are achieved through theembodiment described above.

(1) The image sensor 3 includes a plurality of filter units 5, thetransmission wavelength of which can be adjusted, a plurality ofphotoelectric conversion units 34 that receive light having beentransmitted through the filter units 5 and a control unit (filtercontrol unit 60) that alters the size of a first region that contains afirst filter unit 5, among the plurality of filter units 5, which allowslight at a first wavelength to be transmitted and enter a photoelectricconversion unit 34. This structure enables the filter control unit 60 toalter the size of a region 41 that includes an R pixel, a region 42 anda region 43 each of which includes a G pixel, and a region 44 thatincludes a B pixel, by controlling the individual filter units 5. Inaddition, the filter control unit 60 is able to alter the size of aBayer array basic unit by controlling the filter units 5 so as to setthe same transmission wavelength range for the filter units 5 in aplurality of pixels adjacent to one another.

(2) The filter control unit 60 in the embodiment alters the size of theregions 41 through 44 while sustaining the Bayer array pattern. Thismeans that a signal generated by adding together the signals generatedat a plurality of pixels 10 adjacent to one another can be output. Sincesignals at same-color pixels adjacent to one another are added together,the level of noise in the signal and the level of current consumptioncan be lowered in comparison to levels of noise and current consumptionin an image sensor that generates a signal by adding together signalsgenerated at same-color pixels disposed at positions set apart from oneanother. In addition, the length of time required for pixel signalreadout can be reduced in comparison to the length of time required toread out signals each generated by adding together signals generated atpixels disposed at positions set apart from one another.

SECOND EMBODIMENT

In reference to FIG. 12, the image sensor in the second embodiment willbe described. The image sensor 3 in the second embodiment adjusts thepixel signal readout area, to an area 120A, 120B or 120C incorrespondence the zoom magnification factor selected for the electroniczoom function of the electronic camera 1, and adjusts the transmissionwavelength ranges for the filter units 5 in the pixels 10 present in thereadout areas 120A through 120C, as indicated in FIGS. 6(a) through6(c).

FIG. 12(a) shows the pixel signal readout area 120A set when arelatively high magnification factor is set for the electronic zoomfunction and the array pattern with which R pixels, G pixels and Bpixels are set within the readout area 120A. FIG. 12(b) shows the pixelsignal readout area 120B set when an intermediate magnification factoris set for the electronic zoom function and the array pattern with whichR pixels, G pixels and B pixels are set within the readout area 120B.FIG. 12(c) shows the pixel signal readout area 120C set when arelatively low magnification factor is set for the electronic zoomfunction and the array pattern with which R pixels, G pixels and Bpixels are set within the readout area 120C.

The readout area 120A in FIG. 12(a) includes a Bayer array reiteratingbasic unit made up with 2×2=4 pixels, i.e., one R pixel, two G pixelsand one B pixel. Namely, in the readout area 120A, a region 41A where asingle R pixel is present, a region 42A and a region 43A each containinga single G pixel, and a region 44A where a single B pixel is presentconstitute the Bayer array basic unit, in the same manner as shown inFIG. 6(a). Such regions 41A, 42A 43A and 44A are set by controlling thefilter units 5 in the individual pixels 10 via the filter control unit5.

The readout area 120A for high magnification zoom is selected byensuring that the number of pixels 10 in the readout area 120Asubstantially matches the number of display pixels disposed at anexternal display device with a relatively high resolution that isutilized by, for instance, the photographer when viewing photographicimage data. It is to be noted that the selection may be made by thephotographer as he enters the number of display pixels at the displaydevice into the camera 1 by operating an operation member (not shown) atthe electronic camera 1 and sets the readout area 120A based upon theentered number of display pixels thus input. Pixel signals generated atthe pixels 10 within the readout area 120A are read out throughprocessing similar to the readout processing described in reference toFIG. 8.

For purposes of simplifying the illustration, the readout area 120A inthe example presented in FIG. 12(a) contains 6×6 pixels. Namely, in theexample presented in FIG. 12(a), i.e., in high magnification zoom, theimage sensor 3 outputs 36 pixel signals.

The readout area 120B in FIG. 12(b), selected for electronic zoom at anintermediate magnification factor, is set greater than the readout area120A corresponding to a high magnification factor shown in FIG. 12(a).In more specific terms, it is set to take up an area four times the areaof the readout area 120A. In the readout area 120B, a region 41B, where2×2=4 R pixels are present, a region 42B and a region 43B eachcontaining 2×2=4 G pixels, and a region 44B where 2×2=4 B pixels arepresent are set in a Bayer array pattern, in the same manner as shown inFIG. 6(b). Such regions 41B, 42B, 43B and 44B are set by controlling thefilter units 5 in the individual pixels 10 via the filter control unit5.

The image sensor 3 reads out a sum pixel signal generated by addingtogether pixel signals at the four R pixels in the region 41B and readsout a sum pixel signal generated by adding together pixel signals at thefour G pixels in the region 42B in the readout area 120B. Likewise, theimage sensor 3 reads out a sum pixel signal generated by adding togetherpixel signals at the four G pixels in the region 43B and reads out a sumpixel signal generated by adding together pixel signals at the four Bpixels in the region 44B in the readout area 120B. Namely, in theexample presented in FIG. 12(b), i.e., in intermediate magnificationzoom, the image sensor 36 outputs sum pixel signals just as it outputs36 pixel signals for high magnification zoom.

The readout area 120C in FIG. 12(c), selected for electronic zoom at alow magnification factor, is set even greater than the readout area 120Bcorresponding to an intermediate magnification factor shown in FIG.12(b). In more specific terms, it is set to take up an area nine timesthe area of the readout area 120A for high magnification zoom. In thereadout area 120C, a region 41C, where 3×3=9 R pixels are present, aregion 42C and a region 43C each containing 3×3=9 G pixels, and a region44C where 3×3=9 B pixels are present are set in a Bayer array pattern,in the same manner as shown in FIG. 6(c). Such regions 41C, 42C, 43C and44C are set by controlling the filter units 5 in the individual pixels10 via the filter control unit 5.

The image sensor 3 reads out a sum pixel signal generated by addingtogether pixel signals at the nine R pixels in the region 41C and readsout a sum pixel signal generated by adding together pixel signals at thenine G pixels in the region 42C in the readout area 120C. Likewise, theimage sensor 3 reads out a sum pixel signal generated by adding togetherpixel signals at the nine G pixels in the region 43C and reads out a sumpixel signal generated by adding together pixel signals at the nine Bpixels in the region 44C in the readout area 120C. Namely, in theexample presented in FIG. 12(c), i.e., in low magnification zoom, theimage sensor 3 outputs 36 sum pixel signals just as it outputs 36signals for high magnification zoom and intermediate magnification zoom.

As described above, the filter control unit 60 in the second embodimentcontrols the filter units 5 in the individual pixels 10 so as to set asingle R pixel in the region 41A in FIG. 12(a), set four R pixels in theregion 41B in FIG. 12(b) and set nine R pixels in the region 41C in FIG.12(c). Likewise, the filter control unit 60 sets a single G pixel ineach of the regions 42A and 43A in FIG. 12(a), sets four G pixels ineach of the regions 42B and 43B in FIG. 12(b) and sets nine G pixels ineach of the regions 42C and 43C in FIG. 12(c). Likewise, the filtercontrol unit 60 sets a single B pixel in the region 44A in FIG. 12(a),sets four B pixels in the region 44B in FIG. 12(b) and sets nine Bpixels in the region 44C in FIG. 12(c). Thus, the filter control unit 60is able to set a fixed number of pixel signals or sum pixel signals tobe output from the image sensor 3 regardless of the zoom magnificationsetting by adjusting the size of a filter unit 5, which is controlled toassume a given transmission wavelength range, in correspondence to theelectronic zoom magnification setting.

The image sensor 3 in the embodiment as described above is capable ofoutputting a fixed number of pixel signals or sum pixel signals incorrespondence to all the zoom magnification settings that may beselected for electronic zooming, and is thus able to sustain a givenlevel of resolution for images to be brought up at display devices.

In addition to advantages and operations similar to those of the firstembodiment, the following advantage and operation are achieved throughthe embodiment described above.

(3) The total number of signals obtained via a plurality ofphotoelectric conversion units 34 having received light transmittedthrough a plurality of first filter units under first control and thetotal number of sum signals generated by adding together signalsgenerated via a plurality of photoelectric conversion units 34 havingreceived light transmitted through a first region under second controlare substantially equal to each other. The total number of signalsobtained through a plurality of photoelectric conversion units 34 havingreceived light transmitted through a plurality of second filter unitsunder the first control and the total number of sum signals generated byadding together signals generated via a plurality of photoelectricconversion units 34 having received light transmitted through a secondregion under the second control are substantially equal to each other.As a result, the same number of pixel signals or sum pixel signals canbe output at all the zoom magnification settings that may be selectedfor electronic zooming. Ultimately, a uniform resolution can besustained in images displayed at display devices.

The following variations are also within the scope of the presentinvention, and one of the variations or a plurality of variations may beadopted in combination with either of the embodiments described above.

Variation 1

In reference to drawings, the image sensor 3 in variation 1 will beexplained. It is to be noted that in the figures, the same referencesigns are assigned to elements identical to or equivalent to those inthe first embodiment and that the following explanation will focus onfeatures differentiating the image sensor in variation 1 from the imagesensor 3 in the first embodiment. FIG. 13 is a circuit diagram showingthe structure in part of the image sensor 3 in variation 1. The columncircuit unit 80 includes switch units SW11 (SW11 a through SW11 f),switch units SW12 (SW12 a through SW12 f), switch units SW13 (SW13 athrough SW13 f), arithmetic operation circuit units 83 (arithmeticoperation circuit units 83 a through 83 f), and a switch control unit84. A switch unit SW11, a switch unit SW12, a switch unit SW13 and anarithmetic operation circuit unit 83 are disposed in correspondence toeach pixel column made up with a plurality of pixels 10 disposedside-by-side along the column direction, i.e., along the longitudinaldirection. In addition, the pixels 10 in variation 1 do not includefirst switch units 18.

ON/OFF control of the switch unit SW11, the switch unit SW12 and theswitch unit SW13 is executed by the switch control unit 84. Thearithmetic operation circuit unit 83, which may be constituted with, forinstance, an amplifier circuit, has a function of executing additionprocessing for adding together a plurality of signals input thereto. Inthe embodiment, the pixel vertical drive unit 70, the second switchunits 19, the capacitances FD, the switch unit SW11, the switch unitSW12, the switch unit SW13 and the arithmetic operation circuit unit 83together function as an adder unit that adds together signals from thephotoelectric conversion units 34.

FIG. 14 illustrates how an operation may be executed in the image sensor3 in variation 1. FIG. 14(a) presents an example in which a Bayer arrayreiterating basic unit is made up with 2×2 pixels each present in one ofregions 41A through 44A. FIG. 14(b) is a timing chart of an operationthat may be executed in the image sensor 3 when the transmissionwavelengths are set for the filter units 5 as shown in FIG. 14(a). InFIG. 14(b), time points are indicated along the horizontal axis. Inaddition, SW11 (SW11 a through SW11 f), SW12 (SW12 a through SW12 f) andSW13 (SW13 a through SW13 f) respectively indicate control signals inputto the switch units SW11 (SW11 a through SW11 f), the switch unitsSW12(SW12 a through SW12 f) and the switch units SW13(SW13 a throughSW13 f). In the timing chart in FIG. 14(b), a transistor, to which ahigh-level control signal (e.g., at the source potential) is input,enters an ON state and a transistor, to which a low-level control signal(e.g., at the ground potential) is input, enters an OFF state.

At a time point t1, a signal RST1 shifts to high level, thereby settingthe transistors M2 constituting the reset units 26 in an ON state andsetting the potentials at the floating diffusions 27 to the resetpotential at the pixels 10 (1, 1) through 10 (1, 4) in the first row. Inaddition, at the time point t1, a signal SEL1 shifts to high level and,as a result, noise signals originating at the pixel 10 (1, 1) throughthe pixel 10 (1, 4) are respectively output to the vertical signal lines101 a through 101 d via the transistor M3 constituting the amplifierunits 28 and the transistors M4 constituting the selection units 29. Assignals SW11 a through SW11 d shift to high level at the time point t1,the noise signals from the individual pixels 10 in the first row, havingbeen output to the vertical signal lines 101 a through 101 d, arerespectively input to the arithmetic operation circuit unit 83 a throughthe arithmetic operation circuit unit 83 d. The arithmetic operationcircuit units 83 a through 83 d output the signals input thereto to theA/D conversion unit 82 a through the A/D conversion unit 82 drespectively. The A/D conversion units 82 a through 82 d convert thesignals input thereto to digital signals.

At a time point t2, a signal TX1 shifts to high level, thereby settingthe transistors M1 constituting the transfer units 25 in an ON state atthe pixel 10 (1, 1) through the pixel 10 (1, 4) in the first row. As aresult, electric charges, resulting from photoelectric conversionexecuted at the PD11 through the PD14 are respectively transferred tothe capacitance FD11 through the capacitance FD14 at the individualfloating diffusions 27. In addition, since the signal SEL1 is at highlevel at the time point t2, pixel signals generated at the pixel 10 (1,1) through the pixel 10 (1, 4) are respectively output to the verticalsignal lines 101 a through 101 d via the corresponding amplifier units28 and selection units 29. Moreover, since the signals SW11 a throughSW11 d are at high level at the time point t2, the pixel signals outputfrom the pixels 10 in the first row to the vertical signal lines 101 athrough 101 d are respectively input, via the arithmetic operationcircuit units 83 a through 83 d, to the A/D conversion unit 82 a throughthe A/D conversion unit 82 d where they are converted to digitalsignals.

During a time period elapsing between a time point t3 and a time pointt5, noise signals and pixel signals originating at the pixels 10 (2, 1)through 10 (2, 4) in the second row are read out in the same way assignals are read out over the time period elapsing between the timepoint t1 and the time point t3. Likewise, noise signals and pixelsignals originating at the pixels 10 (3, 1) through 10 (3, 4) in thethird row are read out over a time period elapsing between the timepoint t5 and a time point t7, and noise signals and pixel signalsoriginating at the pixels 10 (4, 1) through 10 (4, 4) in the fourth roware read out over a time period elapsing between the time point t7 and atime point t9. Through variation 1 described above, pixel signalsgenerated at the pixels can be individually read out when the regions41A through 44A constituting the Bayer array basic unit are each made upwith a single pixel, as in the first embodiment.

FIG. 15 presents another example of an operation that may be executed inthe image sensor 3 in variation 1. FIG. 15(a) shows a Bayer arrayreiterating basic unit made up with 4×4 pixels present in regions 41Bthrough 44B. FIG. 15(b) is a timing chart of an operation that may beexecuted in the image sensor 3 when the transmission wavelengths at thefilter units 5 are set as shown in FIG. 15(a).

At a time point t1, a signal SW_Y1 shifts to high level, therebyelectrically connecting the capacitances at pixels 10, i.e., thecapacitance FD11 and the capacitance FD21 at the pixels 10 (1, 1) and 10(2, 1), the capacitance FD12 and the capacitance FD22 at the pixels 10(1, 2) and 10 (2, 2), the capacitance FD13 and the capacitance FD23 atthe pixels 10 (1, 3) and 10 (2, 3) and the capacitance FD14 and thecapacitance FD24 at the pixels 10 (1, 4) and 10 (2, 4) are electricallyconnected with each other.

In addition, at the time point t1, a signal RST1 and a signal RST2 shiftto high level, thereby turning on the transistors M2 constituting thereset units 26 and setting the potentials at the floating diffusions 27to the reset potential at the pixels 10 (1, 1) through 10 (1, 4) and thepixels 10 (2, 1) through 10 (2, 4).

At the time point t1, as a signal SEL1 shifts to high level, a noisesignal generated by averaging signals at the two pixels 10 (1, 1), and10 (2, 1) is output to the vertical signal line 101 a via the amplifierunit 28 and the selection unit 29 at the pixel 10 (1, 1). In addition,as the signal SEL1 shifts to high level at the time point t1, a noisesignal generated by averaging signals at the two pixels 10 (1, 2), and10 (2, 2), a noise signal generated by averaging signals at the twopixels 10 (1, 3), and 10 (2, 3) and a noise signal generated byaveraging signals at the two pixels 10 (1, 4), and 10 (2, 4) arerespectively output to the vertical signal line 101 b through thevertical signal line 101 d.

At the time point t1, a signal SW11 a, a signal SW11 c, a signal SW13 aand a signal SW13 c also shift to high level. It is to be noted that asignal SW11 b, a signal SW11 d, a signal SW13 b, a signal SW13 d and thesignals SW12 a through SW12 d are each set to low level. As a result,the noise signal generated by averaging the signals at the two pixels 10(1,1) and 10 (2, 1) output to the vertical signal line 101 a and thenoise signal generated by averaging the signals at the two pixels 10 (1,2) and 10 (2, 2) output to the vertical signal line 101 b are input tothe arithmetic operation circuit unit 83 a where they are added togetherand averaged. Namely, the arithmetic operation circuit unit 83 agenerates a noise signal representing the average of the signals at thefour pixels, i.e., the pixel 10 (1,1), the pixel 10 (2, 1), the pixel 10(1, 2) and the pixel 10 (2, 2), and outputs the noise signal thusgenerated to the A/D conversion unit 82 a. The A/D conversion unit 82 athen converts the signal input thereto to a digital signal.

Likewise, the noise signal generated by averaging the signals at the twopixels 10 (1, 3) and 10 (2, 3) output to the vertical signal line 101 cand the noise signal generated by averaging the signals at the twopixels 10 (1, 4) and 10 (2, 4) output to the vertical signal line 101 dare input to the arithmetic operation circuit unit 83 c where they areadded together and averaged. Namely, the arithmetic operation circuitunit 83 c generates a noise signal representing the average of thesignals at the four pixels, i.e., the pixel 10 (1, 3), the pixel 10 (2,3), the pixel 10 (1, 4) and the pixel 10 (2, 4), and outputs the noisesignal thus generated to the A/D conversion unit 82 c. The A/Dconversion unit 82 c then converts the signal input thereto to a digitalsignal.

At a time point t2, a signal TX1 and a signal TX2 shift to high level,thereby turning on the transistors M1 constituting the transfer units 25to transfer electric charges resulting from photoelectric conversionexecuted at the PD11 through the PD14 and at the PD21 through the PD24to the corresponding floating diffusions at the pixels 10 (1, 1) through10 (1, 4) and the pixels 10 (2, 1) through 10 (2, 4).

In addition, at the time point t2, a sum pixel signal generated byaveraging signals at the two pixels 10 (1, 1) and 10 (2, 1) is output tothe vertical signal line 101 a. Furthermore, at the time point t2, a sumpixel signal generated by averaging signals at the two pixels 10 (1, 2)and 10 (2, 2), a sum pixel signal generated by averaging signals at thetwo pixels 10 (1, 3) and 10 (2, 3) and a sum pixel signal generated byaveraging signals at the two pixels 10 (1, 4) and 10 (2, 4) arerespectively output to the vertical signal line 101 b through thevertical signal line 101 d.

Also at the time point t2, the sum pixel signal generated by averagingthe signals at the two pixels 10 (1, 1) and 10 (2, 1) output to thevertical signal line 101 a, and the sum pixel signal generated byaveraging the signals at the two pixels 10 (1, 2) and 10 (2, 2) outputto the vertical signal line 101 b, are input to the arithmetic operationcircuit unit 83 a where they are added together and averaged. Namely,the arithmetic operation circuit unit 83 a generates a sum pixel signalrepresenting the average of the signals at the four pixels, i.e., thepixel 10 (1,1), the pixel 10 (2, 1), the pixel 10 (1, 2) and the pixel10 (2, 2), and outputs the sum pixel signal thus generated to the A/Dconversion unit 82 a. The A/D conversion unit 82 a then converts thesignal input thereto to a digital signal.

Likewise, the sum pixel signal generated by averaging the signals at thetwo pixels 10 (1, 3) and 10 (2, 3) output to the vertical signal line101 c, and the sum pixel signal generated by averaging the signals atthe two pixels 10 (1, 4) and 10 (2, 4) output to the vertical signalline 101 d, are input to the arithmetic operation circuit unit 83 cwhere they are added together and averaged. Namely, the arithmeticoperation circuit unit 83 c generates a sum pixel signal representingthe average of the signals at the four pixels, i.e., the pixel 10 (1,3),the pixel 10 (2, 3), the pixel 10 (1, 4) and the pixel 10 (2, 4), andoutputs the sum pixel signal thus generated to the A/D conversion unit82 c. The A/D conversion unit 82 c then converts the signal inputthereto to a digital signal.

During a time period elapsing between a time point t3 and a time pointt5, signals generated by adding together and averaging signals generatedat the pixel 10 (3, 1), the pixel 10 (3, 2), the pixel 10 (4, 1) and thepixel 10 (4, 2) and signals generated by adding together and averagingsignals generated at the pixel 10 (3, 3), the pixel 10 (3, 4), the pixel10 (4, 3) and the pixel 10 (4, 4) are read out in the same way assignals are read out during the time period elapsing between the timepoint t1 and the time point t3. During a time period elapsing betweenthe time point t5 and a time point t7, signals generated by addingtogether and averaging signals at the pixel 10 (5, 1), the pixel 10 (5,2), the pixel 10 (6, 1) and the pixel 10 (6, 2) and signals generated byadding together and averaging signals generated at the pixel 10 (5, 3),the pixel 10 (5, 4), the pixel 10 (6, 3) and the pixel 10 (6, 4) areread out in the same way as signals read out during the time periodelapsing between the time point t1 and the time point t3. In the abovedescribed manner, a signal can be read out by adding together thesignals at four pixels present in each region in conjunction with aBayer array basic unit constituted with the regions 41B through 44B,each made up with 2×2=4 pixels.

FIG. 16 presents yet another example of an operation that may beexecuted in the image sensor 3 in variation 1. FIG. 16(a) shows a Bayerarray reiterating basic unit made up with 6×6 pixels present in regions41C through 44C. FIG. 16(b) is a timing chart of an operation that maybe executed in the image sensor 3 when the transmission wavelengths atthe filter units 5 are set as shown in FIG. 16(a).

At a time point t1, a signal SW_Y1 and a signal SW_Y2 shift to highlevel, thereby electrically connecting capacitances, i.e., thecapacitance FD11 at the pixel 10 (1, 1), the capacitance FD21 at thepixel 10 (2, 1) and the capacitance FD31 at the pixel 10 (3, 1), withone another. In addition, the capacitance FD12 at the pixel 10 (1, 2),the capacitance FD22 at the pixel 10 (2, 2) and the capacitance FD32 atthe pixel 10 (3, 2), become electrically connected with one another. Thecapacitance FD13 at the pixel 10 (1, 3), the capacitance FD23 at thepixel 10 (2, 3) and the capacitance FD33 at the pixel 10 (3, 3), becomeelectrically connected with one another.

In addition, at the time point t1, a signal RST1, a signal RST2 and asignal RST3 shift to high level, thereby turning on the transistors M2constituting the reset units 26 and setting the potentials at thefloating diffusions 27 to the reset potential at the pixels 10 (1, 1)through 10 (1, 3), the pixels 10 (2, 1) through 10 (2, 3) and the pixels10 (3, 1) through 10 (3, 3). In this situation, the potentials of thefloating diffusions 27 are averaged among the capacitances FDelectrically connected with one another.

Furthermore, as a signal SEL2 shifts to high level at the time point t1,a noise signal generated by averaging signals at the three pixels 10 (1,1), 10 (2, 1) and 10 (3, 1), is output to the vertical signal line 101 avia the amplifier unit 28 and the selection unit 29 at the pixel 10 (2,1). As the signal SEL2 shifts to high level at the time point t1, anoise signal generated by averaging signals at the three pixels 10 (1,2), 10 (2, 2) and 10 (3, 2), is output to the vertical signal line 101 bvia the amplifier unit 28 and the selection unit 29 at the pixel 10 (2,2). As the signal SEL2 shifts to high level at the time point t1, anoise signal generated by averaging signals at the three pixels 10 (1,3), 10 (2, 3) and 10 (3, 3), is output to the vertical signal line 101 cvia the amplifier unit 28 and the selection unit 29 at the pixel 10 (2,3).

At the time point t1, a signal SW12 a, a signal SW11 b and a signal SW13b shift to high level. It is to be noted that a signal SW11 a, a signalSW13 a, a signal SW12 b, a signal SW11 c, a signal SW12 c and a signalSW13 c are all set to low level. As a result, the noise signals outputto the vertical signal line 101 a through the vertical signal line 101 care input to the arithmetic operation circuit unit 83 b where they areadded together and averaged. Namely, the arithmetic operation circuitunit 83 b generates a noise signal representing the average of thesignals at the nine pixels, i.e., the pixel 10 (1,1), the pixel 10 (1,2), the pixel 10 (1, 3), the pixel 10 (2,1), the pixel 10 (2, 2), thepixel 10 (2, 3), the pixel 10 (3,1), the pixel 10 (3, 2) and the pixel10 (3, 3), and outputs the noise signal thus generated to the A/Dconversion unit 82 b. The A/D conversion unit 83 b then converts thesignal input thereto to a digital signal.

At a time point t2, a signal TX1, a signal TX2 and a signal TX3 shift tohigh level, thereby turning on the transistors M1 constituting thetransfer units 25 to transfer electric charges resulting fromphotoelectric conversion executed at the PD11 through the PD13, the PD21through the PD23 and the PD31 through the PD33 to the correspondingfloating diffusions 27 at the pixels 10 (1, 1) through 10 (1, 3), thepixels 10 (2, 1) through 10 (2, 3) and the pixels 10 (3, 1) through 10(3, 3).

In addition, at the time point t2, a sum pixel signal generated byaveraging signals at the three pixels 10 (1, 1), 10 (2, 1) and 10 (3, 1)is output to the vertical signal line 101 a. Furthermore, at the timepoint t2, a sum pixel signal generated by averaging signals at the threepixels 10 (1, 2), 10 (2, 2) and 10 (3, 2), and a sum pixel signalgenerated by averaging signals at the three pixels 10 (1, 3), 10 (2, 3)and 10 (3, 3) are respectively output to the vertical signal line 101 band the vertical signal line 101 c.

Also at the time point t2, the sum pixel signals output to the verticalsignal line 101 a through the vertical signal line 101 c are input tothe arithmetic operation circuit unit 83 b where they are added togetherand averaged. Namely, the arithmetic operation circuit unit 83 bgenerates a sum pixel signal representing the average of the signals atthe nine pixels, and outputs the sum pixel signal thus generated to theA/D conversion unit 82 b. The A/D conversion unit 82 b then converts thesignal input thereto to a digital signal. In the above described manner,the image sensor 3 is thus able to read out a signal by adding togetherthe signals at nine pixels present in each region in conjunction with aBayer array basic unit constituted with the regions 41C through 44C,each made up with 3×3=9 pixels.

Variation 2

In reference to drawings, the image sensor 3 in variation 2 will beexplained. It is to be noted that in the figures, the same referencesigns are assigned to elements identical to or equivalent to those inthe first embodiment and variation 1, and that the following explanationwill focus on features differentiating the image sensor in thisvariation from the image sensor 3 in the first embodiment andvariation 1. FIG. 17 is a circuit diagram showing the structure in partof the image sensor 3 in variation 2. The pixels 10 in variation 2 adopta structure that does not include the first switch unit 18 or the secondswitch unit 19. In variation 2, the pixel vertical drive unit 70, aswitch unit SW11, a switch unit SW12, a switch unit SW13 and anarithmetic operation circuit unit 83 together function as an adder unitthat adds together signals from the photoelectric conversion units 34.

FIG. 18 illustrates how an operation may be executed in the image sensor3 in variation 2. FIG. 18(a) presents an example in which a Bayer arrayreiterating basic unit is made up with 2×2 pixels each present in one ofregions 41A through 44A. FIG. 18(b) is a timing chart of an operationthat may be executed in the image sensor 3 when the transmissionwavelengths are set for the filter units 5 as shown in FIG. 18(a). InFIG. 18(b), time points are indicated along the horizontal axis.

At a time point t1, a signal RST1 shifts to high level, thereby settingthe transistors M2 constituting the reset units 26 in an ON state andsetting the potentials at the floating diffusions 27 to the resetpotential at the pixels 10 (1, 1) through 10 (1, 4) in the first row. Inaddition, at the time point t1, a signal SEL1 shifts to high level and,as a result, noise signals originating at the pixel 10 (1, 1) throughthe pixel 10 (1, 4) are respectively output to the vertical signal line101 a through the vertical signal line 101 d via the transistors M3constituting the amplifier units 28 and the transistors M4 constitutingthe selection units 29. As signals SW11 a through SW11 f shift to highlevel at the time point t1, the noise signals from the individual pixels10 in the first row, having been output to the vertical signal line 101a through the vertical signal line 101 d, are input to the A/Dconversion unit 82 a through the A/D conversion unit 82 d respectivelyvia the arithmetic operation circuit unit 83 a through the arithmeticoperation circuit unit 83 d. The A/D conversion units 82 a through 82 dconvert the signals input thereto to digital signals.

At a time point t2, a signal TX1 shifts to high level, thereby settingthe transistors M1 constituting the transfer units 25 in an ON state atthe pixels 10 (1, 1) through 10 (1, 4) in the first row. As a result,electric charges resulting from photoelectric conversion executed at thePDs 11 through 14 are respectively transferred to the capacitance FD11through the capacitance FD14. In addition, since the signal SEL1 is athigh level at the time point t2, pixel signals generated at the pixels10 (1, 1) through 10 (1, 4) are respectively output to the verticalsignal line 101 a through the vertical signal line 101 d via thecorresponding amplifier units 28 and selection units 29. Furthermore,since the signals SW11 a through SW11 d are at high level at the timepoint t2, the pixel signals output from the pixels 10 in the first rowto the vertical signal line 101 a through the vertical signal line 101 dare respectively input via the arithmetic operation circuit units 83 athrough 83 d, to the A/D conversion unit 82 a through the A/D conversionunit 82 d where they are converted to digital signals.

During a time period elapsing between a time point t3 and a time pointt5, noise signals and pixel signals originating at pixels 10 (2, 1)through 10 (2, 4) in the second row are read out in the same way assignals are read out over the time period elapsing between the timepoint t1 and the time point t3. Likewise, noise signals and pixelsignals originating at the pixels 10 (3, 1) through 10 (3, 4) in thethird row are read out over a time period elapsing between the timepoint t5 and a time point t7, and noise signals and pixel signalsoriginating at the pixels 10 (4, 1) through 10 (4, 4) in the fourth roware read out over a time period elapsing between the time point t7 and atime point t9. Through variation 2 described above, pixel signalsgenerated at the pixels can be individually read out when the regions41A through 44A constituting the Bayer array basic unit are each made upwith a single pixel, as in the first embodiment and variation 1.

FIG. 19 presents another example of an operation that may be executed inthe image sensor 3 in variation 2. FIG. 19(a) shows a Bayer arrayreiterating basic unit made up with 4×4 pixels present in regions 41Bthrough 44B. FIG. 19(b) is a timing chart of an operation that may beexecuted in the image sensor 3 when the transmission wavelengths at thefilter units 5 are set as shown in FIG. 19(a).

At a time point t1, a signal RST1 and a signal RST2 shift to high level,thereby turning on the transistors M2 constituting the reset units 26and setting the potentials at the floating diffusions 27 to the resetpotential at the pixels 10 (1, 1) through 10 (1, 4) and the pixels 10(2, 1) through 10 (2, 4).

As a signal SEL1 and a signal SEL2 shift to high level at the time pointt1, the source terminals of the transistors M3 constituting theamplifier units 28 at the pixel 10 (1, 1) and the pixel 10 (2, 1) becomeelectrically connected with each other via the vertical signal line 101a. Thus, a noise signal generated by adding together and averagingsignals at the two pixels 10 (1, 1) and 10 (2, 1), is output to thevertical signal line 101 a. The noise signal output to the verticalsignal line 101 a is a signal corresponding to the average (value) ofthe potentials at the floating diffusions 27 in the pixel 10 (1, 1) andthe pixel 10 (2, 1).

In addition, as the signal SEL1 and the signal SEL2 shift to high levelat the time point t1, the amplifier unit 28 in the pixel 10 (1, 2) andthe amplifier unit 28 in the pixel 10 (2, 2) become electricallyconnected with each other via the vertical signal line 101 a. Thus, anoise signal generated by adding together and averaging signals at thetwo pixels 10 (1, 2) and 10 (2, 2), is output to the vertical signalline 101 b. Likewise, as the signal SEL1 and the signal SEL2 shift tohigh level at the time point t1, a noise signal generated by averagingsignals at two pixels 10 (1, 3) and 10 (2, 3), and a noise signalgenerated by averaging signals at the two pixels 10 (1, 4) and 10 (2, 4)are respectively output to the vertical signal line 101 c and thevertical signal line 101 d.

At the time point t1, a signal SW11 a, a signal SW11 c, a signal SW13 aand a signal SW13 c also shift to high levels. It is to be noted that asignal SW11 b, a signal SW 11 d, a signal SW13 b, a signal SW13 d andthe signals SW12 a through SW12 d are each set to low level. As aresult, the noise signal generated by averaging the signals at the twopixels 10 (1,1) and 10 (2, 1) output to the vertical signal line 101 aand the noise signal generated by averaging the signals at the twopixels 10 (1, 2) and 10 (2, 2) output to the vertical signal line 101 bare input to the arithmetic operation circuit unit 83 a where they areadded together and averaged. Namely, the arithmetic operation circuitunit 83 a generates a noise signal representing the average of thesignals at the four pixels, i.e., the pixel 10 (1,1), the pixel 10 (2,1), the pixel 10 (1, 2) and the pixel 10 (2, 2), and outputs the noisesignal thus generated to the A/D conversion unit 82 a. The A/Dconversion unit 82 a then converts the signal input thereto to a digitalsignal.

Likewise, the noise signal generated by averaging the signals at the twopixels 10 (1, 3) and 10 (2, 3) output to the vertical signal line 101 cand the noise signal generated by averaging the signals at the twopixels 10 (1, 4) and 10 (2, 4) output to the vertical signal line 101 dare input to the arithmetic operation circuit unit 83 c where they areadded together and averaged. Namely, the arithmetic operation circuitunit 83 c generates a noise signal representing the average of thesignals at the four pixels, i.e., the pixel 10 (1, 3), the pixel 10 (2,3), the pixel 10 (1, 4) and the pixel 10 (2, 4), and outputs the noisesignal thus generated to the A/D conversion unit 82 c. The A/Dconversion unit 82 c then converts the signal input thereto to a digitalsignal.

At a time point t2, a signal TX1 and a signal TX2 shift to high level,thereby turning on the transistors M1 constituting the transfer units 25to transfer electric charges resulting from photoelectric conversionexecuted at the PDs 11 through 14 and the PDs 21 through 24 to thecorresponding floating diffusions 27 at the pixels 10 (1, 1) through 10(1, 4) and the pixels 10 (2, 1) through 10 (2, 4).

In addition, at the time point t2, the amplifier units 28 and the pixel10 (1, 1) and the pixel 10 (2, 1) are electrically connected with eachother, and thus, a sum pixel signal generated by averaging signals atthe two pixels 10 (1, 1) and 10 (2, 1) is output to the vertical signalline 101 a. The sum pixel signal output to the vertical signal line 101a is a signal corresponding to the average of the potentials at thefloating diffusions 27 in the pixel 10 (1, 1) and the pixel 10 (2, 1).Namely, a signal corresponds to the average of the potential based uponthe electric charge resulting from photoelectric conversion executed atthe PD11 at the pixel 10 (1, 1) and the potential based upon theelectric charge resulting from photoelectric conversion executed at thePD21 at the pixel 10 (2, 1).

At the time point t2, a sum pixel signal generated by averaging signalsat the two pixels 10 (1, 2) and 10 (2, 2), a sum pixel signal generatedby averaging signals at the two pixels 10 (1, 3) and 10 (2, 3) and a sumpixel signal generated by averaging signals at the two pixels 10 (1, 4)and 10 (2, 4) are respectively output to the vertical signal line 101 bthrough the vertical signal line 101 d.

At the time point t2, the sum pixel signal generated by averaging thesignals at the two pixels 10 (1, 1) and 10 (2, 1) output to the verticalsignal line 101 a, and the sum pixel signal generated by averaging thesignals at the two pixels 10 (1, 2) and 10 (2, 2) output to the verticalsignal line 101 b, are input to the arithmetic operation circuit unit 83a where they are added together and averaged. Namely, the arithmeticoperation circuit unit 83 a generates a sum pixel signal representingthe average of the signals at the four pixels, i.e., the pixel 10 (1,1),the pixel 10 (2, 1), the pixel 10 (1, 2) and the pixel 10 (2, 2), andoutputs the sum pixel signal thus generated to the A/D conversion unit82 a. The A/D conversion unit 82 a then converts the signal inputthereto to a digital signal.

Likewise, the sum pixel signal generated by averaging the signals at thetwo pixels 10 (1, 3) and 10 (2, 3) output to the vertical signal line101 c, and the sum pixel signal generated by averaging the signals atthe two pixels 10 (1, 4) and 10 (2, 4) output to the vertical signalline 101 d, are input to the arithmetic operation circuit unit 83 cwhere they are added together and averaged. Namely, the arithmeticoperation circuit unit 83 c generates a sum pixel signal representingthe average of the signals at the four pixels, i.e., the pixel 10 (1,3),the pixel 10 (2, 3), the pixel 10 (1, 4) and the pixel 10 (2, 4), andoutputs the sum pixel signal thus generated to the A/D conversion unit82 c. The A/D conversion unit 82 c then converts the signal inputthereto to a digital signal.

During a time period elapsing between a time point t3 and a time pointt5, signals generated by adding together and averaging signals generatedat the pixel 10 (3, 1), the pixel 10 (3, 2), the pixel 10 (4, 1) and thepixel 10 (4, 2) and signals generated by adding together and averagingsignals generated at the pixel 10 (3, 3), the pixel 10 (3, 4), the pixel10 (4, 3) and the pixel 10 (4, 4) are read out in the same way assignals are read out during the time period elapsing between the timepoint t1 and the time point t3. During a time period elapsing betweenthe time point t5 and a time point t7, signals generated by addingtogether and averaging signals at the pixel 10 (5, 1), the pixel 10 (5,2), the pixel 10 (6, 1) and the pixel 10 (6, 2) and signals generated byadding together and averaging signals generated at the pixel 10 (5, 3),the pixel 10 (5, 4), the pixel 10 (6, 3) and the pixel 10 (6, 4) areread out in the same way as signals are read out during the time periodelapsing between the time point t1 and the time point t3. In the abovedescribed manner, a signal can be read out by adding together thesignals at four pixels present in each region in conjunction with aBayer array basic unit constituted with the regions 41B through 44B,each made up with 2×2=4 pixels.

FIG. 20 presents yet another example of an operation that may beexecuted in the image sensor 3 in variation 2. FIG. 20(a) shows a Bayerarray reiterating basic unit made up with 6×6 pixels present in regions41C through 44C. FIG. 20(b) is a timing chart of an operation that maybe executed in the image sensor 3 when the transmission wavelengths atthe filter units 5 are set as shown in FIG. 20(c).

At a time point t1, a signal RST1, a signal RST2 and a signal RST3 shiftto high level, thereby turning on the transistors M2 constituting thereset units 26 and setting the potentials at the floating diffusions 27to the reset potential at the pixels 10 (1, 1) through 10 (1, 3), thepixels 10 (2, 1) through 10 (2, 3) and the pixels 10 (3, 1) through 10(3, 3).

As a signal SEL1, a signal SEL2 and a signal SEL3 shift to high level atthe time point t1, the source terminals of the transistors M3constituting the amplifier units 28 in the pixel 10 (1, 1), the pixel 10(2, 1) and the pixel 10 (3, 1) become electrically connected with oneanother via the vertical signal line 101 a. Thus, a noise signalgenerated by adding together and averaging signals at the three pixels10 (1, 1), 10 (2, 1) and 10 (3, 1) is output to the vertical signal line101 a.

In addition, as the signal SEL1, the signal SEL2 and the signal SEL3shift to high level at the time point t1, the amplifier units 28 in thepixel 10 (1, 2), the pixel 10 (2, 2) and the pixel 10 (3, 2) becomeelectrically connected with one another via the vertical signal line 101a. Thus, a noise signal generated by adding together and averagingsignals at the three pixels 10 (1, 2), 10 (2, 2) and 10 (3, 2) is outputto the vertical signal line 101 b. Likewise, as the signal SEL1, thesignal SEL2 and the signal SEL3 shift to high level at the time pointt1, a noise signal generated by averaging signals at the three pixels 10(1, 3), 10 (2, 3) and 10 (3, 3) is output to the vertical signal line101 c.

At the time point t1, a signal SW12 a, a signal SW11 b and a signal SW13b shift to high levels. It is to be noted that s signal SW11 a, a signalSW13 a, a signal SW12 b, a signal SW11 c, a signal SW12 c and a signalSW13 c are each set to low level. As a result, the noise signals outputto the vertical signal line 101 a through the vertical signal line 101 care input to the arithmetic operation circuit unit 83 b where they areadded together and averaged. Namely, the arithmetic operation circuitunit 83 b generates a noise signal representing the average of thesignals at the nine pixels, 10 (1,1), 10 (1, 2), 10 (1, 3), 10 (2, 1),10 (2, 2), 10 (2, 3), 10 (3, 1), 10 (3, 2) and 10 (3, 3), and outputsthe noise signal thus generated to the A/D conversion unit 82 b. The A/Dconversion unit 83 b then converts the signal input thereto to a digitalsignal.

At a time point t2, a signal TX1, a signal T2X and a signal TX3 shift tohigh level, thereby turning on the transistors M1 constituting thetransfer unit 25, to transfer electric charges resulting fromphotoelectric conversion executed at the PDs 11 through 13, the PDs 21through 23 and the PDs 31 through 33, to the corresponding floatingdiffusions 27 at the pixels 10 (1, 1) through 10 (1, 3) the pixels 10(2, 1) through 10 (2, 3) and the pixels 10 (3, 1) through 10 (3, 3).

In addition, at the time point t2, a sum pixel signal generated byaveraging signals at the three pixels 10 (1,1), 10 (2, 1) and 10 (3, 1)is output to the vertical signal line 101 a. At the time point t2, a sumpixel signal generated by averaging signals at the three pixels 10 (1,2), 10 (2, 2) and 10 (2, 3) and a sum pixel signal generated byaveraging signals at the three pixels 10 (1, 3), 10 (2, 3) and 10 (3, 3)are respectively output to the vertical signal line 101 b and thevertical signal line 101 c.

At the time point t2, the sum pixel signals output to the verticalsignal line 101 a through the vertical signal line 101 c are input tothe arithmetic operation circuit unit 83 b where they are added togetherand averaged. Namely, the arithmetic operation circuit unit 83 bgenerates a sum pixel signal representing the average of the signals atthe nine pixels, and outputs the sum pixel signal thus generated to theA/D conversion unit 82 b. The A/D conversion unit 82 b then converts thesignal input thereto to a digital signal. In the above described manner,the image sensor 3 is thus able to read out a signal by adding togetherthe signals at nine pixels present in each region in conjunction with aBayer array basic unit constituted with the regions 41C through 44C,each made up with 3×3=9 pixels.

In this variation, the amplifier units 28 in the plurality of pixels 10disposed along the column direction are electrically connected with oneanother via a vertical signal line 101 so allow signals generated in theplurality of pixels 10 to be added together at the vertical signal line101. Thus, the need for the second switch units 19 via which the signalsat a plurality of pixels 10 disposed along the column direction areadded together and the wiring for connecting the second switch units 19to the floating divisions 27 is eliminated. In addition, since thesignals generated at the plurality of pixels 10 disposed along the rowdirection are added together in an arithmetic operation circuit unit 83,the need for the first switch units 18 via which the signals in theplurality of pixels 10 disposed along the row direction are addedtogether and the wiring for connecting the first switch units 18 to thefloating divisions 27, is eliminated. Consequently, the pixels can beminiaturized and the chip area of the image sensor can be reduced.

Furthermore, when signals generated at pixels are added together byconnecting a plurality of amplifier units 28 with one another, anaccurate sum cannot be calculated unless the difference among thesignals at the individual pixels 10, to be added together, i.e., thepotential differences among the potentials at the floating diffusions 27in the individual pixels, is small. For instance, if there is asignificant difference between the potentials at the floating diffusions27 in two addition-target pixels, almost all of the electric currentfrom the current source 81 will flow to the amplifier unit 28 in thepixel with the higher level signal, and in such a case, a signalcorresponding to the average of the potentials at the two floatingdiffusions 27 cannot be obtained. In contrast, the regions 41A through44A, 41B through 44B and 41C through 44C in the variation each containsame-color pixels 10 and thus, the difference among the signals at theindividual pixels 10 to be added together is expected to be small. As aresult, accurate addition processing can be executed in this variation.

Variation 3

In variation 2, signals generated at a plurality of pixels 10 disposedalong the column direction are added together at a vertical signal line101 and signals generated at a plurality of pixels 10 disposed along therow direction are added together in an arithmetic operation circuit unit83. As an alternative, signals generated at a plurality of pixels 10disposed along the column direction and signals generated at a pluralityof pixels 10 disposed along the row direction may both be added togetherat a vertical signal line 101. FIG. 21 is a circuit diagram showing thestructure in part of the image sensor 3 in variation 3. The columncircuit unit 80 in variation 3 does not include arithmetic operationcircuit units 83. Timing charts pertaining to operations that may beexecuted in the image sensor 3 in variation 3, which would be identicalto the timing charts in FIGS. 18 through 20, are not provided and theseoperations will not be explained in detail. The following explanationwill focus on primary differences from the image sensor 3 in variation2.

At the time point t1 in FIG. 19, a signal SEL1, a signal SEL2, a signalSW11 a and a signal SW13 a shift to high level, thereby electricallyconnecting the amplifier units 28 at the pixel 10 (1, 1), the pixel 10(1, 2), the pixel 10 (2, 1) and the pixel 10 (2, 2) with one another viathe vertical signal lines 101 a and 101 b. As a result, a noise signalgenerated by averaging signals at the four pixels 10 (1, 1), 10 (1, 2),10 (2, 1) and 10 (2, 2) is output to the A/D conversion unit 82 a whereit is converted to a digital signal. Likewise, as a signal SW11 c and asignal SW13 c shift to high level at the time point t1, a noise signalgenerated by averaging signals at the four pixels 10 (1, 3), 10 (2, 3),10 (1, 4) and 10 (2, 4) is output to the A/D conversion unit 82 c whichthen converts it to a digital signal.

At the time point t2 in FIG. 19, a signal TX1 and a signal TX2 shift tohigh level and a sum pixel signal generated by averaging signals at thefour pixels 10 (1, 1), 10 (1, 2), 10 (2, 1) and 10 (2, 2) is output tothe A/D conversion unit 82 a where it is converted to a digital signal.Likewise, at the time point t2, a sum pixel signal generated byaveraging signals at the four pixels 10 (1, 3), 10 (2, 3), 10 (1, 4) and10 (2, 4) is output to the A/D conversion unit 82 c which then convertsit to a digital signal.

During the period of time elapsing between the time point t3 and thetime point t5 in FIG. 19, signals generated by adding together andaveraging signals generated at the pixel 10 (3, 1), the pixel 10 (3, 2),the pixel 10 (4, 1) and the pixel 10 (4, 2) and signals generated byadding together and averaging signals generated at the pixel 10 (3, 3),the pixel 10 (3, 4), the pixel 10 (4, 3) and the pixel 10 (4, 4) areread out in the same way as in the signal readout executed during thetime period elapsing between the time point t1 and the time point t3.During the period of time elapsing between the time point t5 and thetime point t7, signals generated by adding together and averagingsignals generated at the pixel 10 (5, 1), the pixel 10 (5, 2), the pixel10 (6, 1) and the pixel 10 (6, 2) and signals generated by addingtogether and averaging signals generated at the pixel 10 (5, 3), thepixel 10 (5, 4), the pixel 10 (6, 3) and the pixel 10 (6, 4) are readout in the same way as the signal readout executed during the timeperiod elapsing between the time point t1 and the time point t3.

At the time point t1 in FIG. 20, a signal SEL1, a signal SEL2, a signalSEL3, a signal SW12 a, a signal SW11 b and a signal SW13 b shift to highlevel. In response, the amplifier units 28 at the pixel 10 (1, 1), thepixel 10 (1, 2), the pixel 10 (1, 3), the pixel 10 (2, 1), the pixel 10(2, 2), the pixel 10 (2, 3), the pixel 10 (3, 1), the pixel 10 (3, 2)and the pixel 10 (3, 3) become electrically connected with one anothervia the vertical signal lines 101 a, 101 b and 101 c. As a result, anoise signal generated by averaging signals at the nine pixels 10 (1,1), 10 (1, 2), 10 (1, 3), 10 (2, 1), 10 (2, 2), 10 (2, 3), 10 (3, 1), 10(3, 2) and 10 (3, 3) is output to the A/D conversion unit 82 b where itis converted to a digital signal.

At the time point t2 in FIG. 20, a signal TX1, a signal TX2 and a signalTX3 shift to high level. As a result, a sum pixel signal generated byaveraging signals at the nine pixels 10 (1, 1), 10 (1, 2), 10 (1, 3), 10(2, 1), 10 (2, 2), 10 (2, 3), 10 (3, 1), 10 (3, 2) and 10 (3, 3) isoutput to the A/D conversion unit 82 b, which then converts it to adigital signal.

In variation 3 described above, in conjunction with the Bayer arraybasic unit constituted with the regions 41B through 44B each containing2×2=4 pixels, signals generated at the four pixels in each region areadded together at a vertical signal line 101. In variation 3 describedabove, in conjunction with the Bayer array basic unit constituted withthe regions 41C through 44C each containing 3×3=9 pixels, signalsgenerated at the nine pixels in each region are added together at avertical signal line 101. As a result, the need for arithmetic operationcircuit units 83 used for adding together signals generated in aplurality of pixels 10 disposed along the row direction is eliminated.Consequently, the chip area of the image sensor can be reduced.

Variation 4

In the embodiments and the variations thereof described above, thefilter units 5 each include three filters constituted with an EC layer21 that produces Mg (magenta) color, an EC layer 22 that produces Ye(yellow) color and an EC layer 23 that produces Cy (cyan) color. As analternative, the filter units 5 may be configured so that they eachinclude three filters constituted with an EC layer that produces R (red)color, an EC layer that produces G (green) color and an EC layer thatproduces B (blue) color. In addition, the filter units 5 may be variablefilters constituted of liquid crystal.

Variation 5

In the embodiments and the variations thereof described above, R pixels,G pixels and B pixels are formed by controlling the filter units 5 ofthe individual pixels 10. As an alternative, the filter units 5 at thepixels 10 may be controlled so as to form W pixels, each having a W(white) filter unit 5, and BK pixels each having a BK (black) filterunit 5. In such a case, the size of a region where W pixels with W(white) filter units 5 are present and the size of a region where BKpixels with BK (black) filter units 5 are present may be individuallyaltered.

Variation 6

In the embodiments and the variations thereof described above, thephotoelectric conversion units are each constituted with a photodiode.As an alternative, photoelectric conversion units each constituted witha photoelectric conversion film may be used.

Variation 7

The image sensor 3 in the embodiments and the variations thereof is aback-illuminated image sensor. As an alternative, the image sensor 3 maybe configured as a front-illuminated image sensor having a wiring layer210 disposed on the entry surface side where light enters.

Variation 8

The image sensor 3 having been described in reference to the embodimentsand the variations thereof may be adopted in a camera, a smart phone, atablet, a built-in camera in a PC, an on-vehicle camera, a camerainstalled in an unmanned aircraft (such as a drone or a radio-controlledairplane) and the like.

While the present invention has been described in reference to variousembodiments and variations thereof, the present invention is not limitedto the particulars of these examples. Any other mode conceivable withinthe scope of the technical teaching of the present invention is withinthe scope of the present invention.

The disclosures of the following priority applications are hereinincorporated by reference:

Japanese Patent Application No. 2016-192249 filed Sep. 29, 2016Japanese Patent Application No. 2017-61131 filed Mar. 27, 2017

REFERENCE SIGNS LIST

3 image sensor, 5 filter unit, 10 pixel, 34 photoelectric conversionunit, 60 filter control unit,

1. An image sensor, comprising: a filter through which wavelengths oflight to be transmitted can be adjusted; a plurality of photoelectricconversion units that generate electric charge by performing aphotoelectric conversion light transmitted through the filter; and acontrol unit that controls the filter so that number of photoelectricconversion units that perform the photoelectric conversion of lightpassing through a first region that allows light at a first wavelengthto pass are equal to number of photoelectric conversion units thatperform the photoelectric conversion of light passing through a secondregion that allows light at a second wavelength to pass. 2-10.(canceled)
 11. The image sensor according to claim 1, wherein: thefilter constitutes a plurality of filters; and each of the plurality ofphotoelectric conversion units performs the photoelectric conversion oflight having passed through each of the plurality of filters.
 12. Theimage sensor according to claim 11, wherein the control unit controlsnumber of the filters, among the plurality of filters, included in thefirst region and number of the filters, among the plurality of filters,included in the second region.
 13. The image sensor according to claim11, wherein the control unit controls number of the filters, among theplurality of filters, included in the first region to be equal to numberof the filters, among the plurality of filters, included in the secondregion.
 14. The image sensor according to claim 11, wherein the controlunit controls number of filters included in the first region to be equalto number of filters included in the second region adjacent to the firstregion.
 15. The image sensor according to claim 11, wherein the controlunit controls the filter so as to change at least one of a position anda size of the first region and the second region.
 16. The image sensoraccording to claim 11, wherein the control unit controls numbers offilters to be included in the first region and the second region so thatat least one of a position and a size of the first region and the secondregion changes.
 17. The image sensor according to claim 11, wherein thecontrol unit controls numbers of the filters included in the firstregion and the second region so that a size of the first region is equalto a size of the second region adjacent to the first region.
 18. Theimage sensor according to claim 11, wherein the control unit controlsthe filters so that number of the photoelectric conversion units thatperform the photoelectric conversion of light having passed through thefirst region, number of the photoelectric conversion units that performthe photoelectric conversion of light having passed through the secondregion and number of photoelectric conversion units that perform thephotoelectric conversion of light passing through a third region thatallows light at a third wavelength to pass are equal.
 19. The imagesensor according to claim 18, wherein the control unit controls numbersof the filters included in each of the first region, the second regionand the third region adjacent to the first region and the second regionto be equal.
 20. The image sensor according to claim 18, wherein thecontrol unit controls numbers of the filters included in each of thefirst region, the second region and the third region so that a size ofthe first region, a size of the second region and a size of the thirdregion are equal.
 21. The image sensor according to claim 18, whereinthe control unit controls the first region, the second region and thethird region to form a Bayer array.
 22. The image sensor according toclaim 1, further comprising: an adder unit that adds together a signalbased upon the electric charge generated at the photoelectric conversionunit in the first region and adds together a signals based upon theelectric charge generated at the photoelectric conversion unit in thesecond region.
 23. The image sensor according to claim 22, furthercomprising: an accumulating unit that accumulates the electric chargegenerated at the photoelectric conversion unit; wherein the adder unitadds together the electric charge generated at the photoelectricconversion unit in the first region by connecting the accumulating unitsincluded in the first region and adds together the electric chargegenerated at the photoelectric conversion unit in the second region byconnecting the accumulating units included in the second region.
 24. Theimage sensor according to claim 23, further comprising: a plurality ofaccumulating units; and a plurality of connecting units that are capableof connecting the plurality of accumulating units; wherein the pluralityof connecting units are disposed along a first direction and along asecond direction intersecting the first direction.
 25. An image sensor,comprising: a filter through which light to be transmitted can beadjusted; a plurality of photoelectric conversion units that perform aphotoelectric conversion of light that has passed through the filter;and a control unit that controls the filter so that a first regioncontaining the filter, through which light at a first wavelength passes,a second region containing the filter, through which light at a secondwavelength passes and a third region containing the filter, throughwhich light at a third wavelength passed to form a Bayer array.
 26. Theimage sensor according to claim 25, wherein the control unit controlsthe filters so that number of the photoelectric conversion units thatperform the photoelectric conversion of light having passed through thefirst region, number of the photoelectric conversion units that performthe photoelectric conversion of light having passed through the secondregion and number of photoelectric conversion units that performphotoelectric conversion of light passing through the third region areequal.
 27. The image sensor according to claim 25, wherein the filterconstitutes a plurality of filters; and each of the plurality ofphotoelectric conversion units performs the photoelectric conversion oflight having passed through each of the plurality of filters.
 28. Theimage sensor according to claim 1, wherein at the filter, which includesa first electrode and a second electrode, the wavelength of light to bepassing is altered based upon a voltage applied to the first electrodeand the second electrode; the first electrode and the second electrodeare used commonly by a plurality of filters; and the control unitcontrols the voltage to be applied to the first electrode and the secondelectrode.
 29. An electronic camera, comprising: the image sensoraccording to claim 1; and an image generation unit that generates imagedata based upon a signal provided by the image sensor.